Table of Contents 1 2 3 4 5 6 7 8 9 10 11
Team Qualification Site Analysis Design Goals and Concepts Envelope Durability Constructability HVAC System Selection and Design Indoor Air Quality Energy Analysis Domestic Hot water, Lighting and Appliances Innovation, Feasibility and Impacts Financial Analysis
Catalog of Figures and Tables Site Analysis
Design Goals and Concepts
Constructability HVAC System Selection and Design
Indoor Air Quality Energy Analysis
Domestic Hot water, Lighting and Appliances
Figure 2.1 St. Louis City View Figure 2.2 McPherson neighborhood Housing Figure 2.3 The Loop, on Delmar Blvd Figure 2.4 City and Neighborhood Figure 2.5 Building Type with road system marked Figure 2.6 Vacant Lots Figure 2.7 Site location on McPherson Ave Figure 2.8 McPherson Avenue Street View Table 2.1 St. Louis Weather Data Figure 3.1 Site Plan Figure 3.2 Design concept diagrams Figure 3.3 Street View from West diagrams Figure 3.4 First Floor, central atrium Figure 3.5 Basement Plan Figure 3.6 First Floor Plan Figure 3.7 Second Floor Plan Figure 3.8 Psychrometric Chart Figure 3.9 Fiberglass wythe connector Figure 3.10 Precast double wall On-site Installatio Table 3.1 Psychrometric Table Figure 4.1 A whole wall section Figure 4.2 Thermal gradient through windows frame analysis Figure 4.3 WUFI-WUSTL resilient home wall section Figure 4.4 WUFI simulation of precast concrete wall Figure 4.5 WUFI-generic wall section Figure 4.6 WUFI simulation of typical wood frame wall Table 4.1 Dew point chart. Figure 5.1 Axono Explosion Diagram Figure 5.2 Connector Section Detail A411 Figure 5.3 Connector Photo From B.T. innovation GmbH Figure 6.1 HVAC flow chart Figure 6.2 Weather/Load dynamics Figure 6.3 Equipment Dynamics with load Figure 6.4 The Temperature lag with the use of concrete Figure 6.5 Night Flush Scheme Figure 7.1 The ERV Figure 7.2 Whole House Ventilation Scheme Figure 8.1 Weekly water consumption Figure 8.2 Total kWh and $ per month Figure 8.3 Relationship diagram between temperature and anuually energy usage Figure 8.4 Total kWH per month with different numbers of PV Figure 8.5 Monthly kWh used Figure 8.6 HERS score Figure 8.7 Design Energy Breakdown Figure 9.1 Weekly water consumption Figure 9.2 Irrigation System Layout Table 9.1 Water-Related Appliance Specs Table 9.2 Rain garden Summary Table 9.3 Irrigation Areas summary. Table 9.4 Appliance Chart Table 11.1 Material Quantity and Cost Estimation Table 11.2 Cost Schedule for Fabrication, Logistics, and Installation
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Washington University in St. Louis Team WUSTL "Resilient Home" Project Summary Designed as a gateway demonstration house on the edge of McPherson Avenue, the WUSTL Resilient Home is a collaborative project that aims for renewing the construction and design principles of typical St. Louis residential neighborhood. The overarching goal is to create a high-performance, zero-energy, affordable and resilient house using advanced precast concrete technology and high performance building systems, while achieving the architectural aesthetics.
Relevance to the Goals of the Competition The WUSTL Resilient Home meets both the DOE Zero Energy Ready Home criteria (per competition guidelines), as well as The Sustainability Plan by the city of St. Louis. It aims to “Promote Energy Efficiency and Utilize Cleaner Forms of Energy” through the following strategies: • Encourage home energy efficiency through energy efficiency and conservation programs; • Increase the installed base of renewable energy. As a prototype, the WUSTL Resilient Home will demonstrate to the public that a high-performance, zero energy ready home can be attractive and affordable.
Design Strategy and Key Points
Precast Resilient Home uses a durable and insulated robust precast concrete panels are factory made and assembled on-site. Special designed dry connection methods make field assembly much easier than traditional methods, significantly reducing field labor and material waste.
Location: 5799 McPherson Ave, St. Louis, MO 63112 w2009 IECC Climate Zone: Square Feet: 2200 sqft finished 3292 unfinished basement. Number of Stories: 2 Number of Bedrooms: 3.5 Number of Bathrooms: 2.5 HERS Score:36 without PV, -1 with 28 PV panels Estimated Monthly Energy Costs:
High performance precast concrete structures are disaster, resilient, protecting against storms, seismic events, blast and acoustic control. Passive Using concrete as the main material stabilizes Climate temperature swings for better thermal performance, Control and allows for novel control strategies with smaller mechanical equipment.
DOE Race to Zero Student Design Competition Washington University in St. Louis
Technical Specifications Wall Insulation = 21 Roof Insulation = 21 Foundation Insulation=30 Windows =10 Energy cost = $110 per month without PV = $17.75 per month with PV
1 Team Qualification Team WUSTL believes it can provide the most attractive, comfortable, sustainable, and Zero Energy home design as a participant in the Race to Zero Student Competition. The home will be an excellent demonstration of how prefabricated, self-sufficient, and resilient homes that can mitigate climate change. The home will be designed with a focus on marketability, sustainability, versatility, and visual appeal. In addition to the research and development that will be put into the house during the design and construction phases, the structure also may be used as a test bed for further research and education. Team WUSTL consists of students and faculty from Architecture, Engineering, multidisciplinary design studios and courses specifically designed for Race to Zero. Industrial partnership is the key to the success of the endeavor and will come through companies and professional associations providing expertise, services, supplies and gifts. WUSTL will bring a fresh, ambitious, and original perspective to Race to Zero through the leadership of the next generation of architects and engineers. Washington University in St. Louis has earned prestigious honors and rankings throughout history, making it a rich environment for students, faculty, staff, external partners and other members of the community. Sustainability, as a core priority at Washington University, is clearly visible in the academic, service and scholarly mission of the institution. Washington University has many research centers and laboratories that are generating highly innovative ideas directly related to the advanced studies of solar energy, the built environment, and public health.
Hongxi Yin Lead Faculty: I-CARES Associate Professor, Washington University in St. Louis Dr. Hongxi Yin will serve as the lead faculty and is responsible for the architectural and engineering integration aspects of the project and programmatic direction. Professor Yin is an I-CARES associate professor in advanced building systems and architecture design at Washington University in St. Louis (WUSTL). Prior to working at WUSTL he served as Chief Technology Officer for Broad Homes Industrial Co., one of the largest precast concrete producers in China. Dr. Yin earned a doctorate in building performance and diagnostics from the School of Architecture at Carnegie Mellon University. He was a visiting assistant professor at Purdue University from 2008 to 2010. His primary research interests are building industry/system integration, design intelligence, whole building performance analysis, prefabrication design, construction automation, human health and productivity for resilience and sustainability. In 2013 Prof. Yin served as Site Operation Manager for Solar Decathlon China. He serves as the Director of the Steering Committee for Solar Decathlon Chinaâ€™s 2017 program.
Tim Michels Lead Faculty in building System: President, Energy Resources Group, Inc. Adjunct Professor, Dept. of Energy Environmental & Chemical Engineering, Washington University in St. Louis Mr. Michels has directed energy conservation and alternative fuels designs and studies for Business, Industry, Institutions and Governmental Organizations. Research grants and contracts have lead to the development of a state-of-the-art Computer based Data Acquisition System, including all hardware and software design. ERG has developed a variety of software tools for sale that are used for energy conservation and solar analyses and for utility bill analyses. Multiple grants and contracts have lead to the development of low-cost passive solar adobe home designs for a Native American Tribe under the HUD HOME Grant and to economic development opportunities and enterprises for multiple tribes.
Pablo Moyano FernĂĄndez Faculty Consultant: Senior Lecturer, Washington University in St. Louis, Pablo Moyano is a Senior Lecturer at Washington University in St. Louis, and has more than 10 years of experience teaching design studios and seminars. He is the recipient of the AIA medal for scholastic achievement and professional promise. Through his teaching, Moyano focuses 2
primarily on housing design with a strong emphasis on self-sufficient and sustainable design that is simultaneously assessed at the scales of the city, the building and the user.His comprehensive research in concrete as a sustainable building material and its diverse applications ranging from large scale buildings to pavers and urban furniture is reflected in his seminars and studios.
Liao He, Student Leader, leading architecutral design and construction documents Student: Master of Architecture, Washington University in St. Louis Bachelor of Architecture, Southeast University, Nanjing, China Liao He is an architecture graduate student at Washington University in St. Louis with interest in traditional architecture and architecture construction. He looks more closely at architecture renovation. Liao has done internship work since undergraduate in Nanjing, Shanghai, and Singapore. The most recent one is a half-year internship in SCDA Architects, where he was involved in a more comprehensive process of a project, from Schematic Design to Construction Drawings and also including construction site meetings.
Zifan Wang, Project Leader in design and document editor Student : Master of Architecture, Washington University in St. Louis B. Art and Science, University of Michigan, Ann Arbor, Michigan Zifan is interested in real estate design and development, especially in residential design. She worked as an architecture intern on projects including a hybrid public park master plan for Suzhou Institute of Landscape Architecture Design Co., Ltd, China, and various residential projects. Zifan hopes to design buildings that set creative and aspiring examples of how to achieve sustainability from the means of building science with an integrated-system approach.
Yi Ding, Project Leader in detail designs and documentation planner Student: Master of Architecture, Washington University in St. Louis B. Science, Bowling Green State University, Bowling Green, Ohio LEED Green Associate Yi Ding is interested in sustainable design of architecture itself and its context. She is interested in how to merge the character of nature into architecture and use it to realize green building, human health, and aesthetic design. Yi has worked for architecture firms, government housing development department, and non-profit companies. She is now looking deeper into sustainable design itself, and even more, its market, efficiency, and value.
Kun Cheng, Project Leader in design development, details, and Student: Master of Architecture, Washington University in St. Louis. B. Architecture, Tsinghua University, Beijing, China. Participated in several design-build projects during undergraduate, Kun mainly focused on how to realize the design goal through industrial process and advanced building technology. Kun believes that designing with nature and high efficiency is the future trends of building industry, that sustainable is not just a word, it can be embedded in every design.
Frank Dadfar, leading design development for envelope and building system Student: Masters of Architecture + Masters of Construction Management Washington University in St.Louis Bacherlor of Arts in Architecture, Hobart and William Smith Colleges With an interest that focuses on architecture and built environement through the lens of sustainability, my goal is to built a career that realizes energy and envrionmental issues and uses them as a set of criteria that guide my designs. Having worked in the design industry in China and the U.S. I have gained a perpective that realizes the dierence between money driven architecture and otherwise. 3
Yuelin Yu Student: Candidate for Master of Architecture, Washington University in St. Louis Bachelor of Landscape Architecture, South China University of Technology (SCUT) Yuelin is a March3+ student in Washington University in St. Louis. She worked as Chicago Urbanism Teacher Assistant and Architecture undergraduate studio Teacher Assistant in school and also worked as intern in Dean Sakamoto Architects and Axi:ome Studio during summer. Working on the project of Housing in both Berlin and Korea,
Yi Wang Student: Master of Architecture, Washington University in St. Louis Bachelor of Art, Hobart and William Smith Colleges, Geneva, NY Yi is an enthusiastic designer with an interest in innovation and sustainability. Having participated in Climate Change Conference in Copenhagen, Yi carries environmental concerns into architectural design with the goal of using design to create sustainable lifestyle.
Chenming Zhang Student: Master of Architecture, Washington University in St. Louis Bachelor of Arts, Beijing Foreign Studies University, Beijing, China Chenming is interested in how to create community and make a difference in peopleâ€™s life through architecture design. Chenming focus on building connection between the gaps occurred in city and peopleâ€™s life, such as housing and interstitial landscape in the street.
Kaiyi Chen Student: Master of Computer Science, Washington University in St. Louis B. Software Engineering, Guangzhou University, Guangzhou, China Kaiyi has a lively interest in the field of energy-efficient smart home and the disciplinary applications of Architecture and Computer Science. As a student with the background of software development, Kaiyi also has experience on embedded and real-time system development.
Diego Alarcon Student: MAS in Mechanical Engineering, Washington University in St.Louis BAS in Mechanical Engineering, Washington University in St.Louis BS in Business Administration, Webster University Diego's most valuable experience has come from his work experience with Abengoa. As an operations engineer co-op, he planned detailed engineering projects in waste to biofuel conversion, water treatment and a solar thermal facility. He has experience working with energy efficiency, heat recovery, renewable energy, energy storage systems, energy audits, retrofitting buildings, thermal systems and technical software.
Tarek Shaban Student: Master of Electrical and Systems Engineering, Washington University in St. Louis B. Engineering, American University of Beirut, Lebanon Tarek has interned twice in design consulting firms, and worked on residential as well as commercial projects such as the Hilton Hotel and Dubai Airport. Having studied power systems and renewable energy as an undergraduate, Tarek has the knowledge and passion for energy efficient designs and incorporating new technologies into modern designs.
Jose M. Rodes Student: Master of Science in Mechanical Engineering, Washington University in St. Louis B.S. in Mechanic Engineering and Math-Physics Jose is a Mechanical Engineering graduate student at Washington University in St. Louis. With interests in renewable energy and sustainable design, energy efficiency is its primary career goal. Studies in HVAC, Sustainable Building Systems and a recent participation in an energy audit arouse an interest to participate in this competition. 4
Course Integration The Race to Zero Student Competition project creates many opportunities for educational experiences and multidisciplinary project-based collaborations. The Competition is integrated into the course curriculum throughout all stages of the project in a number of ways. A significant amount of time has been spent investigating new courses and course modules throughout different colleges and departments in the university. In Spring 2016, one seminar “Building performance for a solar powered house” in Architecture is designed primarily for this design competition. One course named “ADVANCED SUSTAINABILITY ANALYSES” in the Department of Energy and Chemical Engineering (EECE) developed for engineering students for this design competition. The courses listed below indicate how Race to Zero Student Competition has been integrated in the course curriculum offered by various schools at WUSTL. Student learning in the classrooms will be primarily focused on the design phases of the project.
A46 ARCH 408P Building Performance for a Solar Powered House This course studies the state of the art of building integrated solar system, and design such a system for a house and assess its performance using computational tools. Topics include the fundamentals of solar energy systems, energy management, and its implications to design, either passive or active approach. The course involves building performance simulations using Ecotect, Energy+, HERS, and other tools. Students will use simulation data to study the relation between design and its performance. A46 ARCH 438 Environmental Systems I This course addresses the relationship between buildings and an expanded idea of context, including ideas of environment, landform, energy, material and space. The class places an emphasis on each student developing his or her own attitude toward architectural sustainability, its role within the design process, and its relationship to architectural form. A46 ARCH 445 Building Systems Building Systems examines the performance and properties of building materials, both traditional and new, through an analysis of assemblies and related systems. Investigations of wood, masonry, steel and concrete and the integration of relevant building systems will provide the fundamental structure for the course. All systems are investigated relative to their architectural purpose, impact on the environment, relationship to culture/context, technical principles and will also consider construction, our profession and the society in which we practice. A46 ARCH 538C Advanced Building Systems The lectures focus on structure and enclosure systems, active and passive climate control systems, natural and artificial lighting systems, mechanical and electrical services for buildings. Technical precedents will be analyzed relative to their performance characteristics and their relationship to other technologies in the building. During the second half of the semester, students conduct an integration exercise. EECE 591 ENERGY AND BUILDINGS This course will be an introduction to energy use in the built environment and means and methods for evaluating and harvesting these financial benefits. It will be based on fundamentals of energy usage in building systems. Building sciences for architectural envelope, heating and cooling systems, lighting, and controls. Building/weather interaction and utility weather regression analyses. Building dynamics and rates of change in energy usage. Students will work in groups to perform an energy audit for a building on campus. EECE 519 ADVANCED SUSTAINABILITY ANALYSES This is a university wide, multidisciplinary design and construction project that will demonstrate the principals of integrative design to foster new housing models that are sustainable, that focus on energy and water efficiency, and that generate and store renewable energy for site usage. 5
Industrial Partners Dukane Precast Inc. is an industrial leader in precast concrete technology. The company offers a variety of precast, prestressed architectural and structural products. The company has committed sustainability through its design, production, and onsite construction services. St. Louis Prestress Inc. is an industrial leader in precast concrete technology. The company offers a variety of precast, prestressed structural products, such as hollow core floor panels. The company has committed sustainability through its design, production, and on-site construction services. Thermomass manufactures a full line of insulatino systems for use in concrete construction. With over 35 years of experience, they are the industry leader in concrete sandwich wall technology and can help create walls that maximize energy-efficiency, durability, and performance
mark jaffe development co.
Mark Jaffe Development Co. is a residential real estate development company. The company builds single family detached houses in St. Louis' Central West End region. Some properties utilize Natural Gas Condensing Tankless hot water heaters, Geo Thermal Climate Control Systems & Photovoltaic Solar Panels.
Hydro-Temp has many years of experience in working with designers of high performance structures. They also have the most energy efficient geothermal heat pump for the last for consecutive years as certified by Energy Star.
Trusted in more than 500,000 homes, the Unico SystemÂŽ fits into homes where conventional heating and cooling units canâ€™t, providing customers beautiful home with comfort and efficiency for years to come. Located in Farmington, NH, ERG provides machining and general services to Power Generation facilities since 1984. Specific to Steam Turbine Generator Systems ERG, provides diagnostic services, turn key overhauls, reverse engineered replacement parts, dismantlement, transportation, remanufacture, controls upgrade, installations, heat exchanger repairs, etc. Refer to section 6 in Volume II for industrial support letters. 6
2 site Analysis 2.1 City and the Neighborhood St. Louis, like many Midwestern cities, expanded in the early 20th century due to industrialization, which provided jobs to new generations of immigrants and migrants from the South. It reached its peak population of 856,796 at the 1950 census. Suburbanization from the 1950s through the 1990s dramatically reduced the city’s population, as did restructuring of industry and loss of jobs. The effects of suburbanization were exacerbated by the relatively small geographical size of St. Louis due to its earlier decision to become governmentally independent of the county. In the 21st century, the city of St. Louis contains only 11% of the total metropolitan population, while among the top 20 metro areas in the United States, the central cities contain an average of 24% of total metropolitan area population. Although small increases in population have taken place in St. Louis during the early 2000s, overall the city lost population from 2000 to 2010. Urban revitalization becomes a major theme for St. Louis city planning and urban design, and St. Louis architects strive to deliver better solutions. Neighborhood like McRee, as featured in the book of ‘Rebuilding the American City’ by David Gamble, and Patty Heyda, who is a member of the WUSTL faculty, is a good example of how old neighborhood becomes revitalized through “new environmentally-minded green homes”. The buildings were designed in contemporary styles but fit within reigning historic dimensions and organizational layouts extant in the neighborhood.
Figure 2.1. St. Louis City View
Figure 2.2 McPherson Neighborhood Housing
Our site, for Race to Zero Student Competition the McPherson Neighborhood, located just northwest of St. Louis’ central core, as illustrated in Figure 2.4, has an attractive geographical location as it is located close to major city assets and resources, including Washington University, a nationally prominent private university, Forest Park, the seventh largest urban park in the United States, the Saint Louis Art Museum, and the Missouri History Museum. Its adjacency to these important city attractions makes it potentially a healthy and safe neighborhood to dwell in. Figure 2.3 The Loop, on Delmar Blvd
Figure 2.4 City and Neighborhood
2.2 The McPherson Neighborhood The McPherson neighborhood is designed to be pedestrian-friendly. The site can be accessed through secondary roads and street parking is provided for the households. The main road is located few blocks away so the site maintains easy access to major transportation arteries while sustaining a quiet residential environment for the Resilient Home project. As indicated in Figure 2.5, the surrounding building types are mainly residential. Within one mile (walking distance) of the site, there are two metrolink stations: the Debaliviere Metro Station and the Delmar Loop Metro Station. Easy access to such public transportation assets makes it a valuable area for local developers. The adjacency of the site to the Delmar Loop, one of the busiest commercial streets in St. Louis, enhances the vibrancy of the area and makes the area more desirable for young families. As illustrated in Figure 2.6, the existing houses on McPherson are a mixture of single-family houses and multi-family houses. Older residences are masonry and newer construction is wood frame, generally with brick veneers for compatibility with the aesthetic of the area. The older masonry homes perform poorly in terms of energy efficiency. New constructions on previous developed lots have been conducted for several cases on this street. Although their energy performance has been significantly improved, the opportunity is there to reach Zero Energy Ready home as desired by Department of Energy (DOE). Figure 2.6 shows that there are many vacant lots in this neighborhood, and hence the market of energy-efficient, good-quality and aesthetically appealing homes has real potential here.
Figure 2.5 Building Type with road system marked
Figure 2.6 Vacant Lots
2.3 Site Team WUSTL selected a corner site, 40 feet wide (east to west) and 124 feet long (north to south), for Race to Zero design competition. It is located at the intersection of the McPherson Avenue and Laurel Street as shown in Figure 2.7. A local developer provided plans of newly developed homes that have been selling well in the area. This was the starting point for Team WUSTLâ€™s design of an urban single-family house for the Race to Zero Student Competition that preserves many of the visual characteristics of the existing neighborhood. The long lot axis along has a western exposure to Lauel Street. This presents Team WUSTL with a typical urban challenge of passively managing design heating and cooling loads with historically established plat patterns that are difficult at best.
Figure 2.7. Site location on McPherson Ave
2.4 St. Louis Climate St. Louis lies in the US Building America climate zone classification of Mixed-Humid and the International Energy Conservation Code (IECC) Climate Zone 4 and IECC Moisture Regime A. The Table below provides some basic weather data of St. Louis Table 2.1 St. Louis Weather Data
2009 IECC Climate Zone Lattitude Winter Design DB Temp Summer Design DB Temp Summer Design WB Temp Sky Cover Annual Average Ground Temp Cooling Degree Day(CDD) 65F Heating Degree Day(HDD) 65F Annual Hours of Sun Annual Clear Day Average Daily Solar Radiation
Value Climate Zone 4 38.75 N 29 82 77 80% 56 1555 4846 3459 101 4.18 kWh/m2/day
Reference 2009 IECC Residential Prescriptive Requirements
ASHRAE 2009 Fundamentals ASHRAE 2009 Fundamentals ASHRAE 2009 Fundamentals 2006 Virginia Plumbing Code National Weather Service EPW PAMA PAMA CurrentResults.com CurrentResults.com Insolation Data Manual
Figure 2.8 McPherson Avenue Street View
3 Design goals and concepts Team WUSTL, through this Resilient Home project, will educate the public about this new paradigm of adaptive state-of-the-art net-zero houses and how it will affect the dynamics of living. Therefore, the key objective of Team WUSTL will be to develop a flexible human-in-loop architectural design to meet the physical, social, and emotional needs of the residents that will adapt to changes in the household. The house also will showcase the integration of reliable cutting-edge and proven technologies in an innovative, effective, and sustainable way. Team WUSTL will design the house with the followed targeted improvements to conventional technology:
Energy efficiency : passive design; natural ventilation, daylihgting, thermal mass, integrated high performance enclosure and mechanical, electrical, and plumbing support systems. Net-zero energy: renewable energy; heat recovery. Sustainability: water reuse and recycle; carbon neutral; lean fabrication and construction. Resilience: water recycling; precast concrete. Smartness: advanced sensors and network; energy management; data visualization.
3.1 Architectural Design 3.1.1 Site Strategy The layout of the house and the garage is similar to its neighborhood. The main facade of the house is loosely facing south, as indicated in the Figure 3.1 Site plan. The front yard is kept with a similar dimension to existing houses. The space in between the garage and the house is designed as a garden for the household. Street accesses to the site are provided from south, west and north. The major challenge for this site is due to its location: the crossing of two streets makes our house the very front face of the McPherson Avenue. Thus, the exterior appearance of the house is significantly important. The western facade, which is usually hidden when a house is between two other homes, is now exposed to the public and becomes a design opportunity. Therefore, considerable attention was paid to the west facade as well as the front (south) facade in designing apertures, shading, and other design elements. The effort is made to make sure that on one hand, the house stands out as an innovative design, and on the other, it also blends in well with its neighbors. Team WUSTL decided in the early design stages that the house will have a pitched roof, with a north-and-south orientation, and that the southern roof would be used for solar PV installation.
Figure 3.1. Site Plan Refter to construction document A101
3.1.2 Concept Design Integrated with Energy Performance The project itself is designed as a demonstration of integrat- ing advanced building technology to show how prefabricated, self-sufficient, and resilient homes can mitigate climate change and be visually appealing at the same time. The basic pitched roof shape is designed to resonate with the neighborhood. The de- sign concept, however, is to embrace a passive thermal strategy and to make the building stand out from its neighbors. The overall footprint of the home was kept similar to the original design supplied from local developers. The concept diagrams show how we approached the site: in order to enhance the con- cept of passive solar heat gain, we divided the mass into three parts, northern section, middle section and southern section. The major axis is north-south. The passive solar design strategy revolves around installing large southern windows with a higher SHGC than the other windows. This will have the tendency to locally increase the temperature in these rooms, more effectively charging the building’s thermal mass. The locally warmer air will be circulated to the north zones to distribute the energy from the south zones.
Figure 3.2. Design concept diagrams
A strong vertical design element has been inserted to the mass to create a “central shaft” as illustrated in Figure 1. This was done after carefully studying and analyzing the site. Based on the three-part scheme and the new design challenge of a western facade, the concept of a central shaft emerged. Each of the three volumes has different thermal responses to so- lar heat gain: the southern part will be warmer than the northern part and the central part, with its vertical void, will help with the interior heat transfer and provide an opportunity for ventilation with the natural stack effect. .
3.1.3 Form Design Enhances Energy Performance We increased the southern facade window-to-wall ratio to take more advantage of the passive solar heat gain and the thermal mass effect of concrete. The glass for the south windows have a different Solar Heat Gain Coefficient for the other orientations to maximize winter heat gain. Exterior Shading is carefully designed for western facade to make sure western solar heat gain is mitigated while maintaining the aesthetics of the design. The western stair has been externally articulated as a design element to emphasize the circulation in the space. In response to the resulting structural challenge this presented, the team designed a sandwiched beam with insulation in the middle and glass above the insulation to minimize thermal bridging. We believe the bold design element of the central vertical void justifies itself through the advantage it brings in terms of build- ing performance and architectural space quality. The ventilation does not only occur horizontally on single level but across the whole building. This will help to improve the interior air quality. The interior sunken yard becomes an essential social space for the household. We compensate for the area lost in the atrium volume by adding another bedroom in the “attic”. Overall the usable floor area is not much less than a typical two-story single-family house. An atrium skylight is introduced for a better daylight quality of the central space, special attention is paid to the thermal per- formance of the roof. The roof for the central void is made from insulated concrete with a KalWall® AeroGel fill panel, which has an R-value of 10 (U-value is 0.09).
Figure 3.3. Street View from West
Figure 3.4. First Floor, central atrium
3.1.4 Interior Space Quality Balanced with Energy Performance Creative and technical solutions are applied within a structure to achieve a successful interior environment in this design. The interior design complements the exterior architecture. Consideration for the environmental sustainability of materials is encouraged in this interior design.
Positioning and layout An exterior covered foyer provides a nice transition space for the occupants. The central void design, the living room, and the sunken yard, are shown in Figure 3.5. The dining room and kitchen have an open floor plan to make the interior space connected and spacious. The second floor has three bedrooms with the master bedroom facing south. (Figure 3.6) The other two bedrooms are made identical in order to make sure kids would not have to fight over the better room. The attic bedroom is smaller but has its special position of the whole house. The master bedroom (Figure 3.7) has its own large bathroom; the other 3 bedrooms share one on the second floor. A half bathroom is located on the first floor for guest use. All the bathrooms and the laundry room are positioned in a stacked way to ensure that the wet zones of the house can be handled more easily in terms of plumbing design. This also allows an on-demand, passive recirculating hot-water distribution system to be installed.
Sustainable strategies A truly integrated design process was used to promote less waste and create sustainable space with more integrated systems: Optimizing use of the sun: A skylight in the atrium roof generates a dynamic . The wood mullions over the west window allows light to eneter while providing interior privacy for the street.. Improving indoor air quality: The double height courtyard is designed to create better ventilation and air quality. Green and sustainable materials: Animal and plant fibers such as wool and organic cotton are used in this design. The flooring and wall materials are also selected to be sustainable. Saving water: The layout is designed to place all water fixtures centrally to reduce pipe lengths and hot-water wait time.
Figure 3.5. Basement Plan
Figure 3.6. First Floor Plan
Figure 3.7. Second Floor Plan
3.2 Performance Goals and Highlights 3.2.1 Passive Design Strategy Overlook The primary design solution for St. Louis humid continental climate is embracing good insulation to capture internal gains as well as using thermal mass to store solar heat gain in order to minimize conventional winter heating demand, and control the air quaility via a dynamic interior air transfer. Sun shading on the western and southern sides are also necessary to prevent the interior space from overheating during summer. A skylight and a central void space are integrated to provide both better ventilation and daylighting. The house uses solar panels on the roof to produce site renewable energy. The grey area annotated in the Psychrometric Chart, Figure 3.8, indicates the major passive design strategies we are going to incorporate in our design. As the percentage number suggested, heating and adding humidification during winter are two aspects that will make the living environment more comfortable. The internal heat gain should also be considered as major strategy to warm the house during winter. The need for cooling is relatively small and can be mitigated through natural ventilation for cooling, fan- forced ventilation cooling and high thermal mass night flush. Based on the chart, the design strategy will focus on using passive solar design coupled to the thermal mass provided by concrete floors and exterior walls as well as carefully controlling the solar heat gain from the western facade during summer time.
Table 3.1 Psychrometric Chart Design Strategy Table for St. Louis From Climate Consultant v 6.0
10.7% 10.8% 2.5% 2.6% 1.6% 1.8% 1.6% 1.1% 19.8% 9.2% 6.7% 3.0% 0.0% 11.4% 9.7% 40.3%
1 Comfort 2 Sun Shading of Windows 3 High Thermal Mass 4 High Thermal Mass Night Flushed 5 Direct Evaporative Cooling 6 Two-Stage Evaporative Cooling 7 Natural Ventilation Cooling 8 Fan-Forced Ventilation Cooling 9 Internal heat Gain 10 Passive Solar Direct Gain Low Mass 11 Passive Solar Direct Gain High Mass 12 Wind Protection of Outdoor Spaces 13 Humidification Only 14 Dehumidification Only 15 Cooling, add Dehumidification if needed 16 Heating, add Humidification if needed
934 hrs 950hrs 221 hrs 228 hrs 137 hrs 154 hrs 142 hrs 96 hrs 1734 hrs 808 hrs 588 hrs 262 hrs 0 hrs 999 hrs 847 hrs 3533 hrs
Figure 3.8 Psychrometric Chart Design Strategy for St. Louis From Climate Consultant v 6.0
3.2.2 Heat Retention and Passive Solar Team WUSTL aims to reduce energy consumption of building as much as 60% through our architectural design for heat retention and as much as 20% through passive technologies to passively harvest solar energy and capture free thermal energy (Lechner 2009). Our design will minimize heat loss in the winter, minimize heat gain in the summer, and use lighting efficiently. These things will be achieved through the proper use of form, orientation, insulation, compactness, window size and location, construction materials, and shading devices. We will use thermal mass, high-performance insulation in the envelope with zero thermal bridging and low-e, high-performance windows in combination with operable external shading to block solar gains during the summer and to admit solar gains during the winter. The combined mechanical and natural cross ventilation (mixed-mode ventilation) will be optimized for building cooling. Overnight natural flush will be integrated in the building controls of cooling and ventilation to remove the heat accumulated in the building mass during the day. The cooler nighttime air flushes and cools the warm building mass. Daylighting in our house will maximize the use and distribution of natural daylight throughout the interior thus reducing the need for artificial electric lighting and ensuring visual comfort.
3.2.3 Integrated High Performance Enclosure As a physical interface of spatial, social, and environmental exchange, the building enclosure will be deliberated and designed by using a novel structural system, advanced materials, and innovative compositions incorporating highly creative and digital fabrication details. The designed enclosure will respond to strict enclosure-related performance criteria and will be tested as both generic prototypes and project-specific designs. The house enclosure will consist of four basic systems (architecture, structure, interior, and MEP) for different functions. The structure and MEP systems will be highly standardized for mass production. On the other hand, the interior and architecture layers will be highly customized and will require more interactions between the architects and product engineers.
3.2.4 Precast double wall enlosure system Prefabrication technology will be used for our house to generate the benefits associated with a mass production approach:, reduction of the cost of construction by 20% to 40% compared to traditional on-site construction. The cost savings will come primarily from material and labor savings, as well as the reduced financing needs due to the shorter construction period. Our house will use highly integrated precast double wall panel systems for walls and floors. The double wall panel system process joins two pre-stressed, reinforced concrete panels to make a sandwich panel wall, with unique fiber glass wythe panel connectors. The insulation in- stalled between the two concrete panels will be high R-value closed-cell polyurethane that is partially bio-based. The typical R-values of the double wall panel will range from R-19 to R- 38 when using the 8â€? thick and 12â€? thick exterior walls. The fire ratings are two-hour minimum all the way up to four hours, which is achievable quite easily when utiliz- ing lightweight concrete.
Precast panels reduce air infiltration through the exterior wall. Edge to Edge insulation and non-conductive connectors ensures no thermal bridging. The products from ThermomassÂŽ eliminate the need to cover the rigid foam insulation on either the exterior or interior of the wall.
Figure 3.9 Fiberglass wythe connector
Figure 3.10 Precast double wall On-site Installation
4 envelope durabitlity 4.1 The Envelope The double wall system we use enhaces the thermal performance of the enclosure with integration of different ways of connection. It also deals well with the moisture problem as illustrated in the WUFI study in this section. The use of concrete becomes the natural vapor barrier and no extra coating is needed for the exterior walls. The design of the envelope realizes the goals of ease and speed of construction. Figure 4.1 shows one whole wall section that contains every joint type. Wood Finishing
Detail 1 Detail 2
Thermal insulation board Expansion Bolt
2'' Precast Concrete Roof 4''EPS Insulation Layer 3'' Precast Concrete Roof Thermal Wood Window Frame ( see window schedule) 3'' precast concrete interior wall 4''EPS Insulation 2'' Precast Concrete Exterior Wall
1" Cement Board Coverage 2.5'' Concrete Slab 5'' Space of Truss
10''x4.5'' Air Duct Φ3.5 Ventilation Air Duct
2.5'' Concrete Slab
Detail 3 Φ0.25'' Rebar Mesh
GFRP Wythe Tie
Detail 4 Φ0.25'' Rebar Loop
Connection Joints (refer to Component Schedule 2'' EPS Insulation Concrete Foundation
Figure 4.1 A whole wall section with roof to roof, roof to wall and floor to wall connection Refer to construction document A401
EAST FACADE ROOF-WALL-FOUNDATION DETAIL SCALE: 1/2'' : 1'-00
Our house will use highly integrated prefabricated double wall panel systems for walls, floors and roofs. The double wall panel system will consist of a process whereby two pre-stressed, reinforced concrete panels are joined to make a sandwich panel wall, with fiberglass wythe ties to connect the inner and outer wall layers s. The insulation installed between the two concrete panels will be high R-value closed-cell polyurethane that is partially bio-based. The typical R-values of the double wall panel will be R21 when using the 4" thick exterior walls. The fire ratings are two-hour minimum all the way up to four hours, which is achievable quite easily when utilizing lightweight concrete. The exterior wall was designed as a 2” thick concrete, 4” thick EPS insulation, and 3” thick concrete sandwich prefabricated wall. Concrete is reinforced by a system of rebar mesh, and two layers of concrete are connected by GFRP Wythe Tie to stabilize the wall and minimize insulation movement. Dry connectors from B.T. innovation GmbH® are used between the panels to make assembly easier. The whole envelope is stable, and air-sealed. Backer rod and caulk are used to help seal all joints. Glue will be used as a final sealant to prevent water and moisture penetration. The glue has 20-year life before there is a need for maintenance and replacement. When an exterior wall reaches an aperture, like windows and doors, its 2” exterior concrete is thickened to 4.5”, and window frame mounts over the layer of EPS insulation, which prevents thermal bridging. The thermal performance of the wall is greatly enhanced by the 4” thick EPS insulation. Its moisture control, on the other hand, is enhanced by concrete material itself and the sealant at the joint of walls. The foundation wall uses the same panel as the above grade wall with the addition of another 2” of EPS insulation on the outside for further insulation and protection below grade. The basement slab is built by only two layers: a 3” thick concrete layer over 2” thick EPS insulation board stock. The reason is that the earth itself is stable in thermal performance. Footings are 15” wide and 6” thick concrete reinforced by 0.25” rebar loop. The foundation is sitting on a layer of gravel so water will not stop and gather at foundation. The roof uses the same system as the exterior wall. When designing the roof, special attention was given to drainage problems. A raised edge with metal flashing is built in to prevent rain water entering the joint point. Solar panels and clay tiles are installed to the roof by a hanging system so they can be replaced easily.
Table 4.1 Dew point chart
4.2 Thermal Gradient through Windows Frame analysis A s i n d i c a t e d i n F i g u re 4 . 2 , t h e thermal gradient ( isotherm contours) generated by THERM software, we confirm that our interior surface tempretures are controlled through design decisions to ensure no moisture is condensed on the surfaces. 16
Figure 4.2 Thermal Gradient through Windows Frame analysis
4.3 Hygrothermal Analysis WUFI Hygrothermal pertains to the movement of heat and moisture through buildings. Accurate prediction of hygrothermal is important for preventing early degradation and reduced building service life. WUFI software precisely measures the hygrothermal performance of exterior envelopes. The software analyzes many parameters, like wind-driven rain, climate data, heat storage, moisture storage, and liquid transport to closely define interior and exterior conditions,. Additional parameters define the condition of the building itself, like orientation, coatings, permanence of paint, interior moisture generation, etc. In order to further confirm the higher quality of our building envelope, our building assembly is compared with a typical woodframe wall assembly. In the WUFI analysis shown in Figure 4.4, the relative humidity (shown in green) of our design never reaches 100% at any location throughout the wall system. The exterior layer of concrete itself already stabilizes the moisture inside the wall. The Purple line, illustrating the dew point, is also pretty stable throughout the assembly. The water content (shown in blue) in EPS insulation is almost none. Due to hygroscopic nature of concrete, the water content remains low and stable. In addition, the water content is constantly decreasing through the simulation, it means throughout years, concrete is drying out slowly. All the aforementioned high performance benefits of our assembly are readily apparent when they are compared to the lack of such quality performances marked out in red boxes in Figure 4.6.
Figure 4.3 WUSTL Resilient Home Wall Section Figure 4.4 WUFI Simulation of Precast Concrete Wall
Figure 4.5 Generic Wall Section Figure 4.6 WUFI Simulation of Typical Woodframe Wall
5 Constructibility 5.1 Construction Overlook In the Team WUSTL Resilient Home, the panelized approach involves manufacturing precast sandwich exterior wall panels, interior wall panels, floors, beams and roof components, which are then shipped to a building site for assembly.
The precast components are assembled in sequence. In the Team WUSTL Resilient Home, the windows, doors, pre-cut electrical wiring and chases, lighting track racks, and all exterior fine finishing are highly integrated. The sandwich (double) floor system can use the space between the floor and ceiling for HVAC ducts and electrical chases.
Concrete Sandwitch Roof Slabs
We use The dry panel connection system uses embedded thread and bolts. This makes on-site construction much easier. The Resilient Home has 55 precast components and 300 connecting points. The estimated erection period is about two days for structure and a week for all electrical wiring connections etc. We are expecting to make the building fully function within two weeks.
HVAC System 10’’ Concrete Sandwitch Panel
The advantage of this approach will greatly reduce the cost for the contractor and sub-contractors compared to the traditional approach.
9’’ Wi Preca th EP st Co S in nc sul rete ati on Sand
Figure 5.1 Axono Explosion Diagram Refer to construction document A411
5.2 Connector B.T. innovation GmbH offers prefabricated concrete parts connectors with reasonable prices. The connectors used are called BT-Spannschloss. It is a turnbuckle which is part of an innovative clamping system that uses screw connections and embedded anchors in prefabricated concrete parts. 1 Roof-Internal Wall Connector
Using BT-Spannschloss means prefabricated concrete parts can be assembled without any additional materials or resources. With this technology, there is no cure time like ther is with other joining systems that use on-site poured concrete. The BT Spannschloss joints can immediately bear full load and they generate significant time and cost savings. Advantages of connector: 1.Quick, effective connection of construction elements 2.Building elements can be clamped without additional materials or otherspecial resources 3.Can be combined with all authorized anchorage systems 4.Low net weight 5.Resistant to tensile and shear forces 6.Cost and time savings through reduction of assembly times and elimination of cure times 7.No need for time-consuming individual solutions 8.Can be assembled whatever the weather 9.Precise positioning of the anchor in the manufacturing process via BT magnet technology 10.Approval from the DiBt (German Institute for Building Technology) Berlin 11.Static verification of the chosen construction connection
2 Roof-Exterior Wall Connector
3 Floor-Floor Connector LEGEND Flat Steel Anchor RD + Rebar Hexagon Bolt HSK-M16x40-gv8.8 BT-Spannschloss M16 Hexagon Bolt HSK-M16x60-gv8.8 Pfeifer DB Anchor, RD16 Hexagon Bolt HSK-M16x70-gv8.8 Anchor Bolt M16
4 Wall-Floor Connector
Connector Details Section Detail Figure 5.2 Connector A411
5.3 Installation 1. Place the prefabricated concrete parts next to one another with the hoist, so that the turnbuckles can be inserted, the screw connections properly aligned and loosely fixed by hand. 2. The clamping connections are to be drawn on in parallel and crosswise using a ring ratchet wrench, until the planned joint width is reached or the compression mountings (base plates, elastomer mountings) are firmly clamped. 3. When the prefabricated concrete parts are under tension, the recesses for the tie points can be sealed using grout.
Figure 5.3 Connector Photo From B.T. innovation GmbH.
The joint area can be sealed with appropriate sealing materials and the external filling of the prefabricated concrete parts can be carried out. 19
6 HVAC System Selection and Design Overall Concepts of the systems Flo Se
Bath Room Kitchen
Fir Bath Room
Zone Control Damper ZONE4
85 Gallon Hot Water Tank
Bath Room ZONE3
Cooling Water Return
Mechanical Concept is to have one two ton water to water ground source heat pump. The Hydro-Therm GSHP will produce chilled and hot water for use in one Unico Fan Coil Unit with a 6 row water coil.. This FCU serves the entire home using a high velocity duct system. Supply air will be distributed through the concrete floor slabs. Air will enter the rooms at the floors underneath windows for draft stop. Bathrooms will be exhaust only.
Cooling Water Supply ZONE2
Freel Return From All Zones
Exhaust Air Fresh Air
Figure 6.1 HVAC flow chart
Exhaust Concept will be to continuously ventilate the kitchen, bathrooms, basement and laundry at a total of 200 CFM. The exhaust will go through an air-to-air ERV that will bring in 250 CFM of OAT continuously. This will positively pressurize the home for controlled exfiltration (no worry about infiltration).
6.1 Mechanical System Design Strategies The Manual J thermal analyses establishes the design loads for the home at 25,200 BTU/H for cooling at 95째F DB, 78 째F WB (SHR of .74) and 25,900 BTU/H for heating at 2째F DB Outdoor Air Temperature. Most HVAC design approach is predicated on ignoring the dynamics of the surrounding exterior environment and the integrated design responses available in design and occupant responses that can be include in a true integrative design approach. The elements of the system are: 1)a water to water variable speed Ground Source Heat Pump (GSHP) with Domestic Hot Water priority; 2)a variable speed 6 row, counter-flow fan coil with 4 zone dampers; 3)an energy recovery ventilator that operates at 66% winter and 51% summer energy recovery rates; 4)an 85 gallon Domestic Hot Water (DHW) storage tank and a 40 gallon chilled water storage tank; 5)operable (south windows are motorized) insulating shades in tracks that seal the edges; 6)controls that monitor building occupancy and temperatures in the Passive Solar Direct Gain collection rooms; 7)a whole house ventilation (economizer) system and, 8)the thermal mass of the house itself (600,000+ pounds of concrete, Capacitance = 110,000+ BTU/째F). 20
3000 2500 2000 1500 1000 500 0
Annual Full Load Hours
Equipment Dynamics with Load
% Full Load
The fan affinity laws predict that variable speed operation over the course of the year can reduce operating equipment power usage on the order of 70+% by continuously serving loads at part flow conditions. 6.1 Figure 2, illustrates power usage at part loads. It shows that there is a very non-linear relationship between percent of full load and power needed to meet loads at these points. The full load power curve is flat from roughly 40 – 80 °F. This is the region where the RPM is at its minimum (plant can’t run any lower) and the system uses 1/27 of its rated power: This is approximately 35% of the hours of the year. This means that the equipment is idling or off over 50% of the hours of the year. This is the advantage of Variable Speed equipment compared to systems operating at constant volume. More importantly, however, is the fact that conventional equipment would operate at full load conditions to meet the winter and summer total full load demand of 1029 hours and 983 hours, respectively while the variable speed heat pump has only 512 (50%) and 368 (37%) equivalent full load hours, respectively.
System Operational Deadband
This system is capable of responding to a widely varying Weather/Load Dynamics - St. Louis, Missouri range of conditions. 6.1 Figure 1, Weather and Load Dynamics, 250 illustrates the proposed sequence of operations for the home 200 as an integrated system and load intensity. From 2°F to 55°F 150 the heat pump operates in a heating mode. From 56°F to 70°F (17.5% of the year) the heat pump is off and the thermal mass 100 of the home, in conjunction with the fan coil circulating air, is 50 used to manage the loads (which are primarily internal gains) 0 that average less than 6000 BTU/H. Natural and assisted 0 20 40 60 80 100 Temperature (°F) ventilation is available to cycle cooler air through the house at night to discharge the heat buildup in the mass during diurnal Hours Heating DH Cooling DH hours. From 70°F and up, the GSHP operates in the cooling Figure 6.2 Weather/Load dynamics mode.
Temperature (°F) Full Load Power
Full Load Hours/Year
Figure 6.3 Equipment Dynamics with Load
Figure 6.3 illustrates the theoretical maximum use of energy for conditioning the space using the GSHP. The occupancy and temperature sensors in the home, in conjunction with the zone dampers and operable window shades, work to further reduce cooling and heating demand. When occupancy sensors associated with the four zone dampers sense that the space is unoccupied, the dampers close and the associated zone goes into unoccupied mode and the space temperature is reset to the unoccupied temperature set point and fan speed is reduced based on static pressure sensors. The thermal mass of the zone now is able to engage in either absorbing or releasing heat to accommodate the needs of the space. Should the space temperature rise above the unoccupied set point in one of the southern two passive solar gain spaces, then stage one “cooling” directs the window insulating shades to close automatically to reduce solar gain in the summer. In the winter if there is sunshine and the temperature drops lower than the unoccupied set point, stage one “heating” opens the shades to capture solar heat passively. Stage two in either heating or cooling turns on the fan coil unit to mechanically circulate air in the space to cycle the thermal mass more directly. Please note from the mechanical drawings in Volume 2 that the hollow cores in the concrete floor slabs, as part of the system’s integrative design approach, are used as distribution “ductwork” for the home. This allows the system to more actively charge and discharge the thermal capacitance of the home’s thermal mass. In the “swing” seasons of spring and fall, (17.5% of the time), windows and doors of the house are opened and the heat pump and fan coil units are off. During this period of time, a fan-wall configuration of whole house exhaust fans, (see Figure 7.2) under variable speed control, can be cycled to help extract heat from the home and, if people are in the airstream flow, it provides evaporative cooling. This is an adaptation of the old attic fan approach to cooling.
6.2 Thermal Mass In conjuction with the HVAC system, the thermal mass is used as a complementary system to reduce the need for mechanical heating during winter. Our building have approximately 595,170 pound of thermal mass. The use of thermal mass in our building can reduce peak heating or cooling load, and subsequently building energy consumption, in particular when it is integrated with night ventilation. As our home is located in climatic zone with diurnal temperature difference 15째F, the peak cooling load can be reduced with heavy thermal mass, i.e. large time constant t. If we consider a case with using air conditioning from 8:00 to 19:00, and the time constant of building as 10 hours, we get approximately 5 % reduction in our total cooling loads.
Figure 6.4 The Temperature lag with the use of concrete
The use of thermal mass also helps in delaying peak cooling load, as indicated in Figure 6.4. The maximum temperature of thermal mass at daytime and maximum cooling load requirement occurs at around 16:00, while the maximum outdoor temperature occurs at 15:00. Sunsequently, heat is released from the thermal mass at night time and thermal mass achieves its minimum temperature at around 4:00 in the following day. At night time the indoor air temperature reaches its minimum at around 3:00 while the minimum outdoor air temperature occurs at around 2:00. The variation of temperature can be seen in figure.
Figure 6.5 Night Flush Scheme
7 Indoor Air Quality IAQ begins with building materials and furnishing specifications to eliminate, to the maximum degree possible, the outgassing of noxious VOCs. During the commissioning process, the building will follow the LEED recommended full building flushing process to minimize VOCs introduced during construction. For normal operations, Team WUSTL has built in several operational strategies and mechanical technologies to manage IAQ at a high level. Note that Team WUSTL uses the term Outdoor Air (OA), not Fresh Air, since there is no warranty that the outdoor air will be “fresh”. However, OA is required by codes, based on ASHRAE Standard 62.2, and LEED suggests that IAQ is enhanced when ventilation exceeds the levels required by 62.2. ASHRAE 62.2 (2013) requires a minimum baseline of continuous ventilation with outdoor air (OA) of 135 CFM, based on the square footage and occupancy of the Resilient Home, during occupied hours. Since outdoor air is always used in this process, and since this building will be very tightly sealed (target ACH <0.3, based on tight joints for all exterior concrete wall panels, Passive House qualified windows and door systems, and the lack of combustion appliances in the home), OA will need to be introduced mechanically. Energy efficiency goals are at odds with the code and the LEED suggestions. Team WUSTL responds to and balances these divergent goals (efficiency vs. more OA) in the following ways: 1) For most of the hours of the year, in order to be energy efficient, an ERV recovers energy from the 200 CFM of exhaust from bathrooms, laundry and kitchen areas, as it brings in a continuous 250 CFM of OA. This provides a modest amount of positive pressure while exceeding the ASHRAE 62.2 baseline by almost a factor of two, in response to LEED recommendations. 2) For 17.5% of the year (55<OAT<70°F), OA is more than acceptable for managing temperatures in the space. The house is designed to be able to open windows and take advantage of the natural stack effect of the central atrium to enhance natural ventilation processes, using motorized dampers and, when needed, variable speed fans, under automatic control, to increase flow. Opening windows and using OA does more than accomplish the odor mitigation goals (“freshness”) of ASHRAE 62.2, it provides occupants with a sense of connection to the natural world which bolsters the psyche.
Figure 7.1 The ERV
3) When building sensors know the building is unoccupied, the ERV is turned off. This is expected to be more than 33% of the hours of the year. Combined with 2) above, reductions in OA approach 50%. In addition, to move beyond simple odor mitigation and to assist with generating healthier IAQ, Team WUSTL will employ bi-polar ionization technology in the supply air system to accomplish air purification by precipitating air borne particles, killing mold, bacteria, and viruses while eliminating odors. This bi-polar ionization unit is downstream of a MERV 13 filter. This effort works to make the home healthier. According to EPA maps, the City of St. Louis is on the border between Zones 1 and 2 with respect to radon in the environment (~4 pCi/L). Team WUSTL will put a radon mitigation system in for protection of the occupants.
Figure 7.2 Whole House Ventilation Scheme
8 energy Analysis Energy Analyses
8.1 Energy Profile Analysis
Manual J calculations established the peak heating and cooling loads for the Resilient Home. These calculations are detailed in the appendix. The home is 3292 SF, has a peak cooling load of 25,148 Manual J calculations established the peak heating and cooling loads for the Resilient Home. These calculations are BTU/H (95°F DB/ 78°F WB, 2.1 tons – 1492 SF/ton) and a peak heating load of 25,948 BTU/H. detailed in the appendix. The home is 3292 SF, has a peak cooling load of 25,148 BTU/H (95°F DB/ 78°F WB, 2.1 tons In order to annual energy usage, it was critical understand how the cooling and heating loads – 1492 SF/ton) and a peak heating load of 25,948 BTU/H. vary throughout the day based on the average outdoor air temperature. St Louis long term temperature data were analyzed to establish the number of hours in a typical year (ranged from 2°F to 103°F for 8784 In order to annual energy usage, it was critical understand how the cooling and heating loads vary throughout the hours (leap year – to be conservative)). The Manual J loads were varied by modeling “peak” loads at 5°F day based on the average outdoor air temperature. St Louis temperaturebetween data were analyzed to establish intervals, with interpolation establishing thelong loadsterm at temperatures the 5°F intervals. This the number of hours provided in a typical year (ranged from 2°F to 103°F for 8784 hours (leap year – to be conservative)). a function of energy usage with respect to outdoor temperature. This function, with the The Manual J loads were varied by modeling at 5°F intervals, interpolation establishing theand loads number of annual hours at “peak” each °F loads in a typical year, predictswith the annual energy usage for heating at temperatures between cooling.the 5°F intervals. This provided a function of energy usage with respect to outdoor temperature. This function, with the number of annual hoursoccurs, at each °F average in a typical annualhourly energy To better understand when usage daily data year, were predicts convertedthe to typical usage for heating anduse cooling. over a day. The daily variation was established with the aid of typical loads shapes that are available from the Electric Power Research Institute (EPRI: http://loadshape.epri.com/enduse). These load shapes allowed theoccurs, team to daily establish the hourly load To better understand when usage average data were consumption of the cooling/heating based on the peak converted to typical hourly use over a day. The daily variation was of loads that day. Every that day ofare theavailable year was from established with the consumption aid of typical shapes modeled according to its peak load (function of the Electric Power Research Institute (EPRI: http://loadshape.epri.com/ temperature) and calculated for each day of the year.load enduse). These load shapes allowed the team to establish the hourly Given that the peak cooling load is 1.6kW and the consumption of the cooling/heating based on the peak consumption of peak heating load is 2kW, our load calculations showed that day. Every day of the year was modeled according to its peak load that cooling requires 2200 kWh/year and heating requires (function of temperature) and calculated for each day of the year. 2800kWh/year. Given that the peak cooling load is 1.6kW and the peak heating load is Once temperature dependency was modeled, it 2kW, our load calculations showed that cooling requires 2200 kWh/year was necessary to estimate daily baseloads (loads invariant and heating requires 2800kWh/year. with temperature: lights, appliances, plug loads, etc.). For the base load, we did a surveying of the equipment Once temperature dependency was modeled, it was necessary to available in the house, and their rates of consumption. A estimate daily baseloads (loads invariant with temperature: lights, case study was developed to establish hourly usage per appliances, plug loads, etc.). For the base a to surveying of the week day/weekend day.load, This we wasdid used develop an equipment available in the house, and their rates of consumption. A case average day load curve. The baseload was established as study was developed13.5kWh/day. to establish hourly usage per week day/weekend day. This was used to develop an average dayaload curve. Empirical data from similar homeThe builtbaseload in the Figure 8.1 were Cooling and heating was established as 13.5kWh/day. region (ICF/3000SF/All Electric/GSHP with DHW from desuperheater) available andconsumption were used for comparison. Those data showed a 50% baseload compared to 50% for heating and cooling. This ratio Empirical data from was a similar home builtthe in energy the region (ICF/3000SF/All used to calibrate use model for the Resilient Home. With these reference points, it was Electric/GSHP with DHW fromthat desuperheater) available and were calculated the total housewere load should be 9961 kWh/year. The monthly usage is expected to follow pattern shown in theaTotal and $ per Month chart. used for comparison.the Those data showed 50%kWh baseload compared to 50% for heating and cooling. This ratio was used to calibrate the energy use model for the Resilient Home. With these reference points, it was calculated that the total house load should be 9961 kWh/year. The monthly usage is expected to follow the pattern shown in the Total kWh and $ per Month chart.
Analyzing the actual Ameren Missouri Electric utility bills and kWh usage of a typical residence in St. Louis for 2015 established that the present electric rates in St. Louis are $0.12 and $0.15/kWh for winter (8 months) and summer (4 months) respectively. The annual average rate was $0.13/kWh. It should be noted that actual energy and meter charges were 85% of the bill. The remaining 15% was for energy efficiency program costs and municipal taxes. 24
To better understand when usagethe occurs, average Analyzing actualdaily Ameren Total kWh and $ per month data were converted to typical hourly use over a day. The Missouri Electric utility bills and kWh usage 1200 daily variation was withinthe aid offortypical 140 of aestablished typical residence St. Louis 2015 1100 loads shapes thatestablished are available from the Electric Power 120 that the present electric rates in 1000 Research Institute (EPRI: http://loadshape.epri.com/ 100 St. Louis are $0.12 and $0.15/kWh for 900 enduse). These load shapes allowedand thesummer team to(4establish 80 winter (8 months) months) 800 the hourly load consumption of the cooling/heating based 60 respectively. The annual average rate was on the peak consumption of that day. Every day of the 700 40 $0.13/kWh. It should be noted that actual year was modeledenergy according to its peak load (function of 600 20 and meter charges were 85% of the kWh Cost temperature) andbill. calculated for each day of the year. 500 0 The remaining 15% was for energy 1 2 3 4 5 6 7 8 9 10 11 12 Given that the peak cooling load is 1.6kW and the peak efficiency program costs and municipal Month heating load is our load calculations showed that Analyzing the2kW, actual Ameren taxes. Total kWh and $ per month cooling requires kWh/year and heating requires Missouri Electric utility2200 bills and kWh usage 8.2 for Totalcooling, kWh andand $ per month With this information,1200 total annual costFigure is $330 $337 for heating. The total cost 140 of a2800kWh/year. typical residence of in St. Louis for 2015 operating the building for a1100 whole year is $1320, averaging $110 per month. It needs to be noted that 120 established that the present electric inonly energy bill the household will be paying, as there our electric costrates is the is no gas line in our design, 1000 100 Onceare temperature dependency it was necessary to estimate daily baseloads invariant with St. Louis $0.12 andand $0.15/kWh forwas the building onlymodeled, requires900 electricity for all purposes (heating, cooking etc.). (loads From the graph, please 80 the equipment available temperature: appliances, plug loads, etc.). For the base load, we did a surveying of winter (8 months)lights, andnote summer (4 months) the minima for April and 800 October, this illustrates the benefits of establishing a “deadband” 60 in the house, their rates of consumption. A case study was are developed to (55<OAT<70). establish hourly usage per week day/ respectively. The and annual average rate was operating strategy for times when temperatures moderate 700 40 weekend Itday. Thisbe was usedthat to develop an average day load curve. The baseload was established as 13.5kWh/day. $0.13/kWh. should noted actual The Daily kWh vs. Average Daily Temperature chart graphically establishes the usage of the 600 20 energy and meter charges were 85% of the Resilient Home in the St. Louis Mixed-Humid/Climate Zone 4. Note that the graph also shows the kWh Cost 500 0DHW from desuperheater) Empirical data from a similar home built in the region (ICF/3000SF/All Electric/GSHP with bill. The remaining 15% was for energy operational strategy impact of allowing the thermal of 1 2 3 4 5 6 mass 7 8 the 9 home 10 11 with 12 whole house ventilation to were available were for comparison. Those data showed aMonth 50% baseload compared to 50% for heating and efficiency programand costs and used municipal manage the heating and cooling loads between 55°F and 70°F. The thermal mass benefits are discussed cooling. This ratio was used to calibrate the energy use model for the Resilient Home. With these reference points, taxes. elsewhere. it was calculated that the total total annual house load be cooling, 9961 kWh/year. monthlyThe usage expected to follow the With this information, cost isshould $330 for and $337 The for heating. totaliscost pattern shown in the for Total kWh and Month chart. $110 per month. It needs to be noted that of operating the building a whole year$isper $1320, averaging our electric cost is the only energy bill the household will be paying, as there is no gas line in our design, theonly actual Ameren Missouri utility(heating, bills andcooking kWh usage a typical residence andAnalyzing the building requires electricity forElectric all purposes etc.). of From the graph, pleasein St. Louis for 2015 established that the present electric rates in St. Louis are $0.12 and $0.15/kWh for winter note the minima for April and October, this illustrates the benefits of establishing a “deadband” (8 months) and summer (4 months) respectively. The annual averageare rate was $0.13/kWh. It should be noted that actual energy and meter operating strategy for times when temperatures moderate (55<OAT<70). charges were 85% of the bill. The remaining 15% was for energy efficiency program costs and municipal taxes. The Daily kWh vs. Average Daily Temperature chart graphically establishes the usage of the Resilient Home in the St. Louis Mixed-Humid/Climate Zone 4. Note that the graph also shows the Figure 9.3 showsimpact how the Home systems respond to respective temperatures and how operational strategy of Resilient allowing the thermal mass of the home with whole house ventilation to much annual energy will be used. manage the heating and cooling loads between 55°F and 70°F. The thermal mass benefits are discussed elsewhere.
This plot clearly shows how the Resilient Home systems respond to respective temperatures and how much annual energy will be used.
This8.3plot clearly shows how the Resilient Home systemsenergy respond to respective temperatures and Figure Relationship diagram between temperature and annually usage how much annual energy will be used.
8.2 The PV Impacts Once the PV panels are installed the total electric cost will drop from $110 a month. According to solar data collected by the National Renewable Energy Lab from 1961 – 1991, in St. Louis, MO, see Table 8.1 in Volume II, solar radiation collected by flat-plate collectors at certain tilt angles per month are depicted in the tables shown. The trend, as expected, demonstrates peak radiation during summer months and decreased radiation during winter months. Assuming a fixed tilt, meaning no seasonal repositioning of the solar panels, it’s best to install the panels facing south with tilt at 32.55F for maximum average solar radiation of 4.8 kWh/m2/day from interpolation. Tilt angle is chosen based on a formula from The Renewable Energy Home Handbook: If latitude is between 25F and 50F, use the latitude x 0.76 + 3.1 degrees. (Note: St. Louis latitude is 38.75F). When selecting and installing a photovoltaic system, it’s important to quantify expected solar radiation and the solar panel’s efficiency over time when considering initial costs. Basically, the goal is to select a system in which payback and other factors would be acceptable to a future owner when taking advantage of the incentives and financing available. Team WUSTL selected the LG NeOn 2, 320W 60 Cell model. This model features both an n-type silicon crystal base and monocrystalline, both with important advantages over their counterparts. N-type Si crystals are phosphorusdoped versus p-type which are boron-doped during crystallization. The main advantage is that n-type silicon cells aren’t damaged by light induced degradation (LID) over time, which normally results in an immediate decrease in power output within a few weeks of installation for p-type photovoltaic systems. In addition, monocrystalline solar panels are preferred over polycrystalline panels because they have higher efficiency rates, are more space efficient, and last longer. Therefore, although monocrystalline panels are more expensive, the occupant can install fewer panels and essentially get more bang for a buck. In addition, monocrystalline panel performance does not suffer as much as polycrystalline panel performance as temperature increases. In St. Louis, where summers can be hot, heat can negatively disrupt power production. In addition, in order to further compensate for the effects of heat, panels will be installed83.6% a few efficient inches above the roof to years. allow Energy for convective air to traverse andiskeep panels moderately after twenty-five production loss over time expected with this type ofcool. Note that the optimum tilt angle was calculated as 32.5° south from horizontal. The roof of the dwelling is at a 38° technology, but it’s essential that the modules will still be useful to the consumer after an extensive angle. The annual between these timedifference such as twenty-five years.two tilts is less than 2 kWh of production per year per panel (0.5%), this is approximately 30Using kWh/year, reducing savings $3.90/year – which considered insignificant. the NREL-PV Watts calculator, the team inputisdesign parameters and location and generated
the monthly electrical production from the panels. This we compared to the monthly Resilient Home LG NeON panels have an efficiency of 19.5%, which is competitive among the consumer market. The product has a energy usage in order to decide on the required number of panels we need for operation. The twelve-year linear warranty guaranteeing maximum power or Pmax of 98% after the first year and maximum 0.6% economics of the situation is a driver in this regard and they are dependent on the policies of the local degradation annually after the second year. Pmax is guaranteed to be at least 83.6% efficient after twenty-five years. utility. Presently, solar generation is credited for the full energy charges for the 1M rate structure up to Energy production loss over time is expected with this type of technology, but it’s essential that the modules will still the total monthly kWh usage. If monthly production exceeds the home usage, the extra solar is be useful to the consumer after an extensive time such as twenty-five years. “purchased” by Ameren at $0.025/kWh, Ameren’s avoided cost of making that incremental kWh. This is a financial disincentive for that heavily Using the NREL-PV Watts calculator, the team input impacts the marginal rates of return for Total kWh per month design parameters and location and generated the proceeding to full net zero status. The figure 1200 monthly electrical production from the panels. This to the right illustrates the issue at hand. The 1000 we compared to the monthly Resilient Home energy production of 12 panels(3.84kW) will not usage in order to decide on the required number 800 exceed the monthly demand in any month, so of panels we need for operation. The economics of all PV kWh will have a savings value on the 600 the situation is a driver in this regard and they are order of $0.10/kWh, based on just the energy dependent on the policies of the local utility. Presently, 400 component of the bill.charges However, solar generation is creditedcosts for the fullutility energy Consumption 200 (6.0kW), the amount 12 Panels for the 1M rate installing structure19uppanels to the total monthly kWh 19 Panels needed for net zero status, will significantly usage. If monthly production exceeds the home 0 1 2 3 4 5 6 7 8 9 10 11 12 over produce in the spring by andAmeren fall and many usage, the extra solar is “purchased” at Month kWh will beavoided purchased at of themaking marginalthat cost $0.025/kWh, Ameren’s cost rate of $0.025/kWh. The reduces the incremental kWh. This is a financial disincentive for Figure 8.4 Total kWh per month with different number of PV economic of therates 19 panels to 95%for of the yield on twelve panels. This is still okay, but it is a that heavily impacts thevalue marginal of return needs to be done at a societal level to reduce such disincentives as proceeding to disincentive, full net zerononetheless. status. TheWork figure to the much as possible. This local variation of net metering, however, may be quite reasonable when you right illustrates the issue at hand. The production consider the the utility allowing the grid to be the storage system for PV production, which of 12 panels(3.84kW) willfact notthat exceed the ismonthly allows the home owner to avoid the first costs and maintenance necessary for a battery system. The present estimated cost for PV 26 installation is $3.80/watt. Ameren MO Monthly kWh Used
consider the fact that the utility is allowing the grid to be the storage system for PV production, which allows the home owner to avoid the first costs and maintenance necessary for a battery system. The present estimated cost for PV demand in any month, so all PV kWh will have a savings installation is $3.80/watt. Ameren MO Monthly kWh Used value on the order of $0.10/kWh, based on just the 1300 provides incentives of $0.50/watt and there energy component costs of the utility bill. However, 1100 is a 30% federal tax These two for installing 19 panels (6.0kW), thecredit. amount needed bring the net to $1.81/watt, 900 net zero status,incentives will significantly overcost produce in the which places the net cost per panel at $580 700 spring and fall and many kWh will be purchased at the installed. Annual production will vary, but 500 marginal cost rate of $0.025/kWh. The reduces the on average, with a 20% safety factor for economic value of the 19 panels to 95% of the yield on 300 annual power saved twelve panels. unknowns, This is stillthe okay, but value it is aofdisincentive, 100 is on needs the order of $36/year, a nonetheless. Work to be done at aproducing societal level 2 3 4 5 6 7 8 9 10 11 12 -100 1 paybackasofmuch 16 years. If the home to reduce such simple disincentives as possible. This Month Home Demand 12 PV Panels 19 PV Panels owner the ability to absorb local variation of net has metering, however, maytaxbebenefits quite associated with depreciation, then reasonable when you consider the fact that thethe utility Figure 8.5 Monthly kWh used payback is shorter. At this level of analysis, is allowing the grid to be the storage system for PV the interest rate for financing has been neglected. It is recommended depreciation benefits production, which allows the that home owner to avoid thebe traded off to cover the cost of money at this stage. Financing can be arranged of this PV installation through the City of St. Louis Property first costs and maintenance necessary forfor a 100% battery Assessed Clean Energy (PACE) program. It can be used to fund any renewable efforts that have a system. See Figure 8.4 which shows the monthly change payback of less than 20 years. This would of total kWh consumed per month with differentqualify and it is recommended that at least 3.8 kW be installed. numbers of PV panels. The present estimated cost for PV installation is $3.80/watt. Ameren MO provides incentives of $0.50/watt and there is a 30% federal tax credit. These two incentives bring the net cost to $1.81/watt, which places the net cost per panel at $580 installed. Annual production will vary, but on average, with a 20% safety factor for unknowns, the annual value of power saved is on the order of $36/year, producing a simple payback of 16 years. If the home owner has the ability to absorb tax benefits associated with depreciation, then the payback is shorter. At this level of analysis, the interest rate for financing has been neglected. It is recommended that depreciation benefits be traded off to cover the cost of money at this stage. Financing can be arranged for 100% of this PV installation through the City of St. Louis Property Assessed Clean Energy (PACE) program. It can be used to fund any renewable efforts that have a payback of less than 20 years. This would qualify and it is recommended that at least 3.8 kW be installed.
8.3 HERS Analysis DOE Zero Energy Ready Home Performance Path The DOE Zero Energy Ready Home Performance Path is a methodology through which Team WUSTLâ€™s Resilient Home assesses its energy performance. First, RESNET-accredited Home Energy Rating Software REM/Rate was used first to determine the HERS Index of the DOE Zero Energy Ready Home Target Home through Exhibits 1 and 2. The Target Home configuration has a HERS rating of 52 for the reference home. See Volume II for more details of the Target Home simulation results. A size modification factor is next calculated using the following equation:
The modification factor for WUâ€™s home: (2800/3270).25 = .9619 The HERS Index of the Target Home is calculated next as:
-1 With 28 PV panels
36 Without PV
Figure 8.6 HERS score
We achieve a HERS score of 36 without PV panels, and a HERS sore of -1 with 28 panels, which can cover the whole southern roof. HERS Index Target for the reference home is: 52*.9619 = 50.01 Without renewable energy, WU’s target home needs to achieve a HERS Rating of less than 50 in order to be qualified as a DOE Zero Energy Ready Home. Energy Efficiency Considerations WU’s home has been designed from the ground-up to incorporate novel energy-saving features which interact with each other. These interactions begin at the foundation, and are broken down into eight steps: 1.High Thermal Mass Walls and Floors (Precast Concrete) 2.High Performance Building Envelope a.Install High Performance Fenestration varying SHGC by orientation b.Design for Passive Direct Gain Solar heating c.Monolithic high value insulation with no thermal bridging 3.Use Occupancy sensors to turn systems off when spaces are unoccupied (30% of the time) 4.Design for Passive Air Flow and fan assisted Evaporative Cooling using OA (17% of the time) 5.Use Energy Recovery Ventilator when mechanical HVAC system is running 6.Implement Highly Energy Efficient HVAC Equipment 7.Use Energy Star Lighting and Appliances 8.Add Active Shading/Dynamic insulation systems to windows.
HERS Rating without Solar Energy By implementing these eight design considerations, WU’s house will achieve a HERS rating of 36 with an annual energy consumption of 15,679 kWh. Further details on this design are included in Volume II. The HVAC system design and energy profile is discussed in section 5, and appliances, lighting, and water conditioning will be discussed in section 8. The HERS Rating documents for the draft DOE Zero Energy Ready Home Certificate and energy analysis for WU’s house are available in Volume II.
HERS Rating with Solar Energy With the use of the proposed PV system, the Resilient Home will achieve a HERS rating of -1, generating 524 kWh per year. Details and references for the PV system will be discussed in the next part of this section.
Further HERS Considerations While REM/Rate is RESNET accredited, it doesn’t have the capability to consider three important aspects of the Resilient Home design: 1) the use of high thermal mass to act as an energy flywheel, directly managing small temperature fluctuations. With a high thermal mass home, the HVAC system can be off for more than 17% of the year by storing thermal energy in its precast concrete system, and reduces the peak load requirements for much more of the year, saving more energy than RESNET accounts for. 2) High efficiency LEDs (140 lumens/Watt) for lighting throughout the home allows for 50% savings on lighting costs over the modelled fluorescent bulbs, further improving our home’s performance relative to REM/RATE results. 3) Use of occupancy sensors to turn off systems when the home is unoccupied cannot be modeled. Through other simulations and calculation methods, these modifications reduce the Resilient Home energy requirements such that only 19 solar panels – instead of the 28 panels that are needed to reach Net Zero per the REM/Rate analyses. Fewer panels have a significant economic impact and payback faster.
Figure 8.7 Design Energy Breakdown
9 Domestic Hot Water and lighting Appliances 9.1 Rainwater profile prediction for St. Louis, MO Water is the most valuable resource on the planet and although it is naturally abundant in the United States; people are unaware of how scarce it is becoming due to climate change. The Environmental Protection Agency (EPA) is an organization that cares about water scarcity and sustainability issues. Thus, it has sponsored a program called WaterSense. The main goal of this program is to help consumers identify high performance water-efficient fixtures such as toilets, faucets, showerheads, etc. Several systems are available that can be implemented in residences to minimize water waste and foster r water reuse. For this project, a storm water collection system can be implemented. In addition, two rain gardens in the site will be used to retain rain water so it has time to perk into the soil. The Race to Zero residence has 2.5 bathrooms, a kitchen faucet, dishwasher, and a laundry. Conventionally, one would consider irrigation loads, but since this home will provide irrigation from rainwater and graywater systems, these loads are ignored at this time. Water Sense labeled appliances will be selected for all of these service loads to make sure highly efficient water devices are installed. A list of appliances is shown below with the specified rated flow rate for faucets and showerheads as well as the best available water consumption per flush or cycle for toilets, clothes washer and dishwasher Table 9.1 Water-Related Appliance Specs
With this, a list of assumptions must be generated to design water consumption in the house in order to determine the percentage used for garden and lawn irrigation. 1. 6 toilet uses per person on weekdays with 2 off-sides on weekdays 2. Adults will use showerheads for approximately 10 minutes per shower per week and kids 6 minutes. This will vary in the weekend with a 50% increase. 3. Faucets will be used 10 to 15 minutes every day with the largest usage on the weekend. 4. An average of 22 minutes of kitchen faucet will be used every weekday and a 50% increase will be used on weekends. 5. According to Energy Star, the laundry machine will use an average yearly water consumption of 3054 gallons per year or 8.4 gallons per day. 6. The dishwasher will use a single average daily load. Knowing all these assumptions, the designed annual water consumption is 88816 gallons or 1708 gallons per week. 30
200 150 100
Weekly Water Usage Profile (Gal.)
50 0350 300
200 150 100 50 0 Mon
Figure 9.1 Weekly water consumption
In order to get an accurate rainwater profile to design a proper storm water collector system for the home, the EPA Stormwater calculator software was used. This software uses parameters such as soil type, precipitation, evaporation and climate change data. The software uses 20 years of data to predict average annual rainfall and runoff in inches. The output of this software place average annual rainfall at 41.52 inches. Now, according to the University of California, 1000 square foot of roof can collect approximately 600 gallons of water. In short, it represents an approximation of 0.6 gallons per square feet. When multiplying this quantity by the annual rainwater for the St. Louis, MO region, of. this corresponds to about 90 gallons per day. All storm water will be collected by placing 4’’ wide gutters on the roof perimeter and transporting water to an underground storm water collector system using 3’’ diameter PVC pipes.
9.2 Rain Gardens According to the Rain Garden Manual written by the Native Plant Society of New Jersey, rain gardens are generally determined by parameters such as garden’s depth, soil, length and width. The site is fairly level, so we will assume an approximate slope of 5%. Consequently, this suggests an adequate depth of 6 in. In addition, a soil type must be determined and it is assumed to be mostly silt. The Rain Garden manual assumes a size factor corresponding to the soil type. Thus, a size factor of 0.25 times the available lawn surface area will yield an appropriate rain garden area for our site. Table 9.2 Rain garden Summary.
9.3 Irrigation System The system implemented on the site depends on the pervious area in question, the amount of gallons per minute each sprinkler is able to deliver and the friction losses on pipe flow network. The irrigation design manual provided by RainBird describes types of sprinklers and their shapes, friction losses and how to design an accurate irrigation system for a site. According to this manual, spray sprinklers are widely used for residential areas and their volume flow rate will depend on the manufacturers. Rain Bird’s pop-up sprinklers have an average volumetric flow rate of about 4 gallons per minute (gpm). In the following figure, it illustrates how this flow rate varies by sprinkler’s shape. 31
Table 9.3 Irrigation Areas summary. Each area is shown in Figure 9.2
This suggests that with an average of 15 minutes of irrigation time, a total of 1620 gallons per day (gpd) will be used. In our design, we got an average of 90 gallons per day from storm water collector and about 200 gallons of water per day on waste water system. So, 290 gallons of water can be collected every day, making irrigation system run every 5 to 6 days. For area A and B, we will use a single control valve, since there is no much difference between sprinklerâ€™s pressure and friction losses among them. However, in area C, the friction losses are above the actual sprinkler pressure so the control valve will be different
Figure 9.2 Irrigation System Layout
9.4 Domestic Hot Water In working with the EPA Water Sense program, all hot water fixtures, the clothes washer and the kitchen dishwasher have all been selected for their low flow characteristics. Note that there is a passive gravity circulation system that assures that there is hot water available at fixtures relatively quickly. From each bathroom there is a return line that allows the cooler (denser) hot water to fall back to the hot water storage tank. Note that the last five feet of line for each drop is uninsulated. This allows for the water to cool faster and induces the needed thermosiphon effect. This is thought to be a more appropriate technology approach than installing a circulating pump. It eliminates the need for a pump and the electric power it uses as well as the associated electrical circuit, installation costs and ongoing maintenance costs. Because of the thermosiphon rate of flow is expected to be less than the forced flow of the pump, it is also expected that it will reduce the parasitic losses associated with more rapid flow delivering hotter water in a continuously circulating system.
9.5 Lighting Team WUSTL lighting goals were to secure the most energy efficient lighting equipment on the market. Having a state of the art design and technology not only provided financial benefits from an energy stand point, but the longevity of the lamps saves on life cycle costs. The goal was to pick fixtures and lamp combinations that provide us with the highest lumens per watt output and also provided uniform general lighting patterns in the spaces served. The team decided to focus on LED technology. A wide range of manufacturers’ equipment was reviewed. Most offered systems in the range of 60-70 lumens/watt, which is comparable to current compact florescent “CFL” technology. Several providers provided systems that met the target 125+ lumens/watt, which uses the next generation of LED lamps commercially available. The team selected ERCO fixtures (130-150 lumens/watt) because their track mounting systems would integrate well with the concrete construction technology (factory installed), which allowed ease of installation. These tracks support two separate lighting circuits for better switching options. The fixtures were selected based on minimizing glare and providing distribution patterns needed. The option of simply using normal A-base LED lamps (Philips at 140 lumens/watt) was considered using conventional residential fixtures. Many of the fixtures available were incompatible with the concrete structure (recessed fixtures were structurally inappropriate), but the A-base lamp fixture was ultimately discarded as an option since it would not guarantee persistence of LED technology. With the conventional screw in base, other technologies could replace these LED lamps. The fixtures chosen were ERCO 72813023 Light Board Spotlight Neutral White. This fixture provided us with 1650 lumens at 12W, (137.5 lumens/watt) at 4000K. Although residential homes typically use warm white lamps (2700±K), we decided to go for the neutral white for two reasons. First, LEDs in this range loose efficiency and second, neutral white is much better for task oriented uses like reading and working computers, and it provides high better color rendering index – “CRI” in the 90s. The proper, uniform lighting desired was achieved using a meshed lighting design. In essence that means that we do not have a symmetrical design across the room, they are alternate as presented in the figure below. This would present us with the highest uniformity across the surfaces and ensure we reached the required lighting levels with the least amount of fixtures. Tilt angles for the fixtures were set at 60 and 45 degrees depending on the depth of the room. Motion sensors will be placed in all rooms, corridors and bathrooms. The motions sensor being selected is a combination of a microphone and infrared sensor. So even when someone in the room is not moving, if the sensor senses noise, lights remain on. It is also a self-learning sensor were it is capable of tuning out common noises that constantly occur but are not signals that someone is in the room to prevent turning on when not needed. Note that these occupancy sensors will be used to also manage the operation of HVAC zone dampers and the fan coil unit. Lighting simulations, using Dialux 4.12, give a detailed anaylsis of lighting levels across the room and at different levels. We simulated every room to design the number of fixtures, their placements, and angles to provide uniform lighting levels. The total number of ERCO fixtures need ed is 68. That puts the Resilient Home lighting at 0.24W/SF, which compared well with the ASHRAE 90.1 multi-family home target 0.6W/SF of lighting. This team goals for highly efficient lighting have been met.
Team WUSTL specifications are that all appliances chosen must be at least energy star. Appliances that have a water consumption are selected in the domestic water section. An important factor in selecting every appliance should be the electrical consumption when it is in shadow mode. A lot of energy is usually consumed by appliances when they are not operating. Such losses should be reduced that as much as possible. The devices and appliances listed below and their associated electrical power estimates were used in generating the baseload electric usage for the energy analyses portions of this report. These data were developed from similar equipment on the market and should be considered as the minimum acceptable level of performance with respect to efficiency. 33
Table 9.4 Appliance Chart
10 Innovation, Feasibility and Impacts As indicated in the previous sections, Team WUSTL Resilient Home will incorporate many advanced components and systems to achieve environmental and energy sustainability and resilience, many of which are integrative innovations, including the following. 1) Off-site prefabrication and on-site assembly of permanent structure coupled with plug and play interior system using prefabricated, modular units that can be installed rapidly and ready for immediate use; 2) High performance precast sandwich (double wall) systems coupled with air-based double floor or hollow core radiant cooling and heating panel system that provide thermal storage and healthy indoor air quality; 3) High-performance precast concrete structures are disaster free, such as storm protection, seismic, blast and re resistance, and acoustic control; 4) Mix-mode ventilation supported by operable windows and stack-effect natural ventilation in atrium area; 5) PV integrated solar thermal units that generate electrical power and provide effective thermal energy; 6) Ground source heat pump heater and chiller that provide cost-effective heating and cooling with low ozone depletion and high system performance; The Resilient Home has the potential to provide significant benefits to its users, builders, manufacturers and suppliers, and the nation. The ultimate user will have a comfortable and healthy home environment with a reliable supply of energy at an affordable cost. Builders, manufacturers, component suppliers, and system integrators will see the growth of green building products. The benefits to the nation will include significantly increased energy efficiency, reduced consumption of fossil fuels, reduced pollutant and CO2 emissions, enhanced security, and enhanced economic activity and job creation. The Resilient Home will integrate with local power grid to accommodate any surplus or deficiency in the operation of the system. Its solar-based power and energy system potentially will meet 90% and more of the building demands and truly will enable net-zero and carbon neutral results with significant reductions in energy and greenhouse gas emissions. Our house will be a prototype for integrated high performance net-zero resilient homes. Their experience with this Resilient Home will be the first step for our students to design and build sustainable housing and to enter the clean energy workforce. Our house will be a critical education step in the general public becoming aware of netzero high performance housing, sustainability, and resilience.
11 FINANCIAL ANALYSIS 11.1 Material quantity and cost of building structure The financial analysis section explains the costs of materials, fabrication, construction, and energy consumption. The cash flow analysis of the Resilient Home is based on Race to Zero Competition guidelines provided by the DOE National Renewable Energy Laboratory. Table 1 summarizes the material quantity and cost of the proposed Resilient Home. Concrete, insulation, and rebar are the three primary materials consistently used for building enclosure and enclosure system. The quantity of materials is estimated from the design drawing and model. The cost schedule is estimated from market price of March 2016. The unit cost of concrete is estimated $5/ft3, the unit cost of EPS insulation is estimated $ 3/ft3, and the unit cost of rebar is estimated at $1.2/kg. The total cost of the proposed building is $31,006. Table 11.1 Material Quantity and Cost Estimation
Exterior Wall Interior Wall Roof Ground Beam Double Floor Foundation Others Rebar(total) Total
area ft2 4088.6 ‐ 1208.5 1100 ‐ 3300 ‐ ‐ 3300
Concrete thickness ft 0.42 0.4 0.42 0.25 ‐ 0.8 ‐ ‐
Concrete volume ft3 1637 569 498 259 167 1036 83 32
Insulation thickness insulation volume Total Material Cost ft ft3 USD 0.33 1310 12114 0 0 2845 0.33 399 3686 0.17 172 1811 0 0 835 0 0 5180 0 0 415 0 0 160 3960 31006
11.2 Fabrication, Logistics and Assembly Costs Table 2 shows the estimated cost of fabrication, transportation, and installation of precast sandwich wall panel, hollow core floor panel, and other precast concrete components. These numbers vary depending on project location, manufacturing approach, and local contractor service capabilities, etc. These numbers are checked and verified by PCI certified producers. As indicated in Table 2, the fabrication cost is $9/ft2 of sandwich wall panel, and the $5/ ft2 for hollow core floor panel. The total cost of transportation and installation is about $11/ ft2 building area. We also considered 30% profits for precast concrete producers. The total cost of the structure is about $191,187 for the proposed resilient home. Table 11.2 Cost Schedule for Fabrication, Logistics, and Installation area ft2
Concrete thickness ft
Precast Sandwich Panel Fabrication cost Other costs related to Fabrication Other costs related to Hollow Core Fabrication
Logistics & Installation on site (building area) Connectors for prefabricated panels 7029.3 Other costs related to Logistics Total cost of logistics and installation area ft2 7029.3
Number of Connector
Concrete volume Insulation thickness insulation volume Total Material Cost ft3 ft ft3 USD 6.00 3.00
3x life cycle
10009.6 $157,077 $204,199.86 $68,066.62
Price per unit
Connectors for prefabricated panels 12512 0.8 Total cost Final cost with 30% of profit The cost actually paid by the owner for every life cycle of wood building (30 years)
11.3 Life Cycle Construction Cost The life cycle of a precast concrete building is more than 90 years. The standard life cycle of a conventional wood structure is bout 30 years. The purpose of introducing life cycle cost to the construction cost analysis is to proper comparing the construction cost of a precast concrete home with that of a traditional wood structure home. The life cycle cost of the proposed resilient home is estimated $68,066, using the cost of structure $204,199 divides by three. The life cycle cost is used in construction cost analysis in Table 11.3. The precast concrete sandwich panels, hollow core floor panels, and beams representing the Framing system (items H to L), partial of the Exterior Finishes (items of M & N), and partial of the Interior Finishes (items U & V). The costs of the rest items in Table 3 leave as the default values set by NAHB. The life cycle construction cost of the proposed resilient home is $309,924. W
11.4 Affordability Financial Analysis The ACS 1-year data shows the median family income for St Louis was $72,001 in 2014. In Table 11.4, this number is used to calculate the Debt to Income Ratio. The estimated ratio is about 37% for the proposed resilient home, which is lower than the affordability target 38%. For more detailed analysis, please refer to Table 4: Financial Analysis Summary and Table 11.5: Thermomass Cost Estimation
11.5 Conclusion The financial cost analysis indicates precast concrete resilient home is affordable if considering life cycle cost analysis. In fact, longer life cycle of a home indicates less material use and better sustainability. If considering the potential of using mass production or customization approach to produce precast concrete components. The cost of precast resilient home has the potential to complete with traditional wood structure in its first cost. However, this mass production can only happen when enough quantity of home demands in a concentrated area. This trend may be shown up when the public fully understands the benefits of precast concrete resilient home. We will use this project to initiate the mass scale acceptance of precast concrete resilient home in US.
Reference 1.Lina Yang, Yuguo Li, cooling load reduction by using thermal mass an night ventilation, Energy and Buildings, 40 (2008), page 2052-2058 2.http://rcgb.rutgers.edu/wp-content/uploads/2013/10/Wall-Assemblies_2014_01_24.pdf 3.St Louis Missouri Household Income, http://www.deptofnumbers.com/income/missouri/st-louis/#household 4.Analyzed Unit Cost Schedule, http://publications.iowa.gov/6278/4/Analyzed_Unit_Cost,_Section_4.pdf 5.ASHRAE 62.2 2007, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings 6.Fonorow, K., Chandra, S., Martin, E., McIlvaine, J., "Energy and Resources Efficient Communities through Systems Engineering: Building America Case Studies in Gainesville, FL.", Proceedings of the 2006 Summer Study on Energy Efficiency in Buildings, American Council for an Energy Efficient Economy, Asilomar, CA., August 2006. Online at http://www.baihp.org/pubs/aceee_fonorow/ ACEEEpaper.pdf 7.Swami, Muthusamy V., Jim Cummings, Raju Sen Sharma, Chuck Withers & Mangesh Basarkar, 2006. Florida Building Code - Enhance Florida's Building To Next- Generation Energy & Mechanical Codes and Enrich Compliance. FSEC-CR-1678-06. Florida Solar Energy Center. Cocoa, Florida. Nov. 29, 2006. 8.Fonorow, K., Chandra, S., McIlvaine, J., Colon, C., "Commissioning High Performance Residences in Hot, Humid Climates", 7th International Conference for Enhanced Building Operations, November 1-2, 2007, San Francisco, California. 9.Avi Friedman, Innovative Houses, Concepts for Sustainable Living, Lawrence King Publishing Ltd, ISBN 978-1-78067293-9 10.David Gamble and Patty Heyda, Rebuilding the American City, Design and Strategy for the 21st Century Urban Core, Routledge, ISBN 978-1-138-79813-7 (hbk)
Published on Mar 27, 2016