Page 1

Final Report


Mary Street Apartments 1 Contents 1

Contents ........................................................................................................................................................................... 2

2

Project Description ........................................................................................................................................................... 4

3

4

2.1

Location: .................................................................................................................................................................... 4

2.2

Site and Building Description: ................................................................................................................................... 4

2.3

Program: .................................................................................................................................................................... 6

2.4

Client Brief : ............................................................................................................................................................... 7

2.5

Scope of Assignment: ................................................................................................................................................ 7

Approach .......................................................................................................................................................................... 8 3.1

Limitations: ................................................................................................................................................................ 8

3.2

Climate Analysis:........................................................................................................................................................ 8

3.3

Understanding Passive House Design: .................................................................................................................... 10

3.4

Considerations: ........................................................................................................................................................ 10

Analysis of existing Schematic Retrofit Design (benchmark) ......................................................................................... 10 4.1

Thermal Boundary ................................................................................................................................................... 10

4.2

Assemblies ............................................................................................................................................................... 11

4.2.1

Ceiling ............................................................................................................................................................... 12

4.2.2

On Grade Walls - External ................................................................................................................................ 13

4.2.3

Floors ................................................................................................................................................................ 14

4.2.4

Basement .......................................................................................................................................................... 15

4.2.5

Windows ........................................................................................................................................................... 16

4.2.6

Doors ................................................................................................................................................................ 17

4.2.7

Assumptions for Lobby and Staircase Extension .............................................................................................. 17

4.2.8

Considerations: ................................................................................................................................................. 18

4.3

5

Building Systems ...................................................................................................................................................... 20

4.3.1

Domestic Hot Water ......................................................................................................................................... 20

4.3.2

Heating / Cooling .............................................................................................................................................. 20

4.3.3

Ventilation ........................................................................................................................................................ 21

4.3.4

Electricity .......................................................................................................................................................... 21

4.3.5

Appliances & Lighting ....................................................................................................................................... 21

4.4

Site / Source Energy Spreadsheet ........................................................................................................................... 22

4.5

Compliance .............................................................................................................................................................. 23

4.5.1

IECC 2012 Guidelines ........................................................................................................................................ 23

4.5.2

HERS Rating Index ............................................................................................................................................ 24

4.5.3

URA Guidelines ................................................................................................................................................. 24

4.5.4

Energy Star Guidelines ..................................................................................................................................... 25

Analysis of Proposed Retrofit Design ............................................................................................................................. 29


5.1

Thermal Boundary Location .................................................................................................................................... 29

5.2

Assemblies .................................................................................................................. Error! Bookmark not defined.

5.2.1

Ceiling .................................................................................................................. Error! Bookmark not defined.

5.2.2

Walls .................................................................................................................... Error! Bookmark not defined.

5.2.3

Floors ................................................................................................................... Error! Bookmark not defined.

5.2.4

Basement ............................................................................................................. Error! Bookmark not defined.

5.2.5

Attic / Roof .......................................................................................................... Error! Bookmark not defined.

5.2.6

Windows – Same as previous model ................................................................... Error! Bookmark not defined.

5.2.7

Doors – Same as previous model ........................................................................ Error! Bookmark not defined.

5.2.8

Considerations ..................................................................................................... Error! Bookmark not defined.

5.3

Building Systems ...................................................................................................................................................... 39

5.3.1

Heating / Cooling .............................................................................................................................................. 39

5.3.2

Water to Air Heat Pumps ................................................................................................................................. 40

5.3.3

Back-up Boiler System ...................................................................................................................................... 42

5.3.4

Heat Sink – Evaporative Condenser ................................................................................................................. 43

5.3.5

Systems Case Study: The Sawmill Building, Lincoln, Nebraska ........................................................................ 44

5.3.6

Benefits & Drawbacks of the California Loop Mechanical System ................................................................... 44

5.3.7

Ventilation ........................................................................................................................................................ 45

5.3.8

Domestic Hot Water ......................................................................................................................................... 46

5.3.9

Electricity .......................................................................................................................................................... 48

5.3.10

Appliances & Lighting ..................................................................................................................................... 50

5.4

Egg Breaking ............................................................................................................................................................ 50

5.4.1

Diffused Lighting LED ........................................................................................................................................ 50

5.4.2

Vertical Spandrel Building Integrated Photovoltaic System ............................................................................. 51

5.5

Compliance.............................................................................................................................................................. 51

5.5.1

IECC 2012 Guidelines ........................................................................................................................................ 51

5.5.2

HERS Rating ...................................................................................................................................................... 53

5.5.3

URA Guidelines Checklist.................................................................................................................................. 53

5.5.4

Energy Star Guidelines ..................................................................................................................................... 54

5.5.5

Passive House Guidelines Checklist .................................................................................................................. 56

5.6

Netting to Zero ........................................................................................................................................................ 57

5.6.1 6

Site / Source Energy Spreadsheet .................................................................................................................... 57

References ...................................................................................................................................................................... 59


2 Project Description 2.1 Location: The Mary Street Apartments project is located in Pittsburgh, Pennsylvania. The building is located in the densely-packed Southside neighborhood in the city. It is well located with easy access to rapid transit and is within walking distance to offices, schools, shopping and entertainment. This is particularly useful as the plot area does not allow for sufficient parking space. It may also be more convenient for some senior citizens to walk to their desired destinations as compared to driving there. The UPMC South Side Hospital is also within walking distance of the building.

Figure 1 –St.Mary’s Church and amenities within walking distance of building

2.2 Site and Building Description: The church and its rectory are located on the plot. The rectory has already been retrofit to house apartments. The buildings together cover almost the entire site with very little open space. The church was built with its boundaries right up to the set-back.


N Figure 2 – Building and Site The long-axis of the building is along the East-West direction. Hence, the long façades of the building face north and south and the shorter facades of the building face the east-west. The main building entrance is along the east façade of the building. The existing church building consists of a basement, first floor and part mezzanine. The building area is 10752 sq.ft (including basement). The mezzanine area is approximately 808 sq.ft. The church has not been functional for the last few years and is currently in a dilapidated state.


2.3 Program: Mary Street Apartments is a retrofit project. The original St. Mary’s church building is to be retrofit to accommodate a Retirement Home. The proposed multi-residence housing facility will contain the following facilities: 

   

14 Apartment Units o 2 Efficiency Units ( ~ 370 sq.ft) o 10 Typical units ( ~ 530 sq.ft) o 2 Accessible Units ( ~ 550 sq.ft) Community Room Washing + Laundry Room Office Rooftop Terrace

The floor areas for the building are –  

First Floor – 5788.5 sq.ft Second Floor – 5788.5 sq.ft


Figure 3 – Floor plan of typical unit

Figure 4 – Floor plan of accessible unit

2.4 Client Brief : The proposed design includes addition of a full mezzanine level which will be the second floor for the retirement home. A complete upgrade of the building envelope and HVAC systems is proposed. The building was to be retrofit to meet Passive House Standards. In addition, the building has to meet the Urban Redevelopment Authority (URA) guidelines, which are based on the new Energy Star v.3 requirements (for new constructions). Compliance to IECC 2012 is also mandatory.

2.5 Scope of Assignment: Attempt has been made to comply with Passive House requirements as well as the URA and IECC 2012 guidelines. The ‘EnerPHit Refurbishment Standard’, which is a good practice refurbishment guide for Passivhaus renovations of existing buildings, has been followed. Certification for EnerPHit Standard can be achieved through two methods. Compliance to method 1 requires achieving the set energy demand criteria. These are – Passivhaus Specific Heat Demand ≤ 15 kWh/sq.m.yr ≤ 4.8 kBtu/sq.ft/yr Primary Energy Usage ≤ 120 kWh/sq.m.yr ≤ 38.1 kBtu/sq.ft/yr Air Infiltration ≤ 0. 6 ACH @ 50 Pa - Target Value

EnerPHit Specific Heat Demand ≤ 25 kWh/sq.m.yr ≤ 8 kBtu/sq.ft/yr Primary Energy Usage ≤ 120 kWh/sq.m.yr ≤ 38.1 kBtu/sq.ft/yr Air Infiltration ≤ 1 ACH @ 50 Pa – Limit Value ≤ 0.6 ACH @ 50 Pa - Target Value

The target was to achieve Energy Star rating through the New Homes Program. This program is applicable for rating units in multifamily buildings with 3 stories or fewer stories above-grade. The rating system requires an individual unit, in worst conditions, to be modeled. This unit is representative of the other units in the building as long as they have same conditions and either same or lesser window-to wall ratios. If it is a multi-storey building, an individual unit has to be modeled for each level.


3 Approach The building was modeled using REM/Rate Version12.96. It was decided to model the whole building as opposed to modeling an individual apartment as the area and hence the conditioning requirement of each unit was very low. In order to propose a code compliant design, the existing retrofit scheme was analysed and a new design was proposed to help improve the thermal performance and energy efficiency of the building.

3.1 Limitations: The client wanted to retain the aesthetics of the external faรงade. Hence, no changes other than those proposed by the architect were made to the external faรงade materials, windows etc.

3.2 Climate Analysis: Pittsburgh has 5957 Heating Degree Days (base 65F) and 5009 Cooling Degree Days (base 74F)1. It falls in the 5A climate zone as per IECC 2012. Climate analysis using Climate Consultant 5.1 indicates that Pittsburgh has only 314 comfortable hours in the year. Owing to the low temperatures and the high relative humidity (> 60%) for most of the year, care should be taken to provide efficient heating systems and reduce humidity. Appropriate design of solar thermal and PV systems for heating, cooling and domestic hot water is critical in Pittsburgh due to the almost 100% annual cloud cover in the city. Thermal massing may be required to counteract the high diurnal changes.

Figure 5 - Psychometric Chart for Pittsburgh

1

REM/Rate Software


Figure 6 – Cloud Cover

Figure 7 – Monthly Diurnal Changes Relevant suggestions by Climate Consultant for the energy efficient design for the retrofit project in Pittsburgh are   

Maximize internal gains by building tight and well insulated Minimize glazing u-factor to minimize conductive loss and gain Super insulation as a cost-effective solution for keeping indoor temperatures more uniform Steep pitched roofs, vented to the outside with a well insulated ceiling below to prevent ice dams and shed rain and snow


Good natural ventilation to reduce or eliminate air-conditioning

3.3 Understanding Passive House Design: Passive House design aims to achieve two goals - minimizing energy losses and maximizing passive energy gains. Passive House designers and builders work to systematically implement the following principles –      

Superinsulation Elimination of Thermal Bridges Airtightness Specification of energy or heat recovery ventilation Specification of high performance windows and doors Optimisation of passive-solar and internal heat gains

It is noted that several suggestions by climate consultant coincide with Passive House design principles.

3.4 Considerations: It is necessary to provide for moisture control within the thermal envelope when building air-tight super insulated buildings in cold humid climate. Lack of efficient moisture control and ventilation strategies can result in mold growth on interior insulation. This will affect the indoor air quality of the homes. Insulation has to be placed on the interior wall surface as the aesthetics of the exterior façade have to be maintained. This will reduce the airtightness as well as moisture control efficiency of the wall.

4 Analysis of existing Schematic Retrofit Design (benchmark) 4.1 Thermal Boundary

Figure 8 – Benchmark Thermal Boundary (First Floor)

An extension including an entrance lobby and a staircase lobby have been proposed. The thermal boundary on the first floor includes the apartment units as well as the proposed extension. It is assumed that a basement will be made for the proposed lobbies. This area has been included in the Conditioned Floor Area (CFA) calculations.


Figure 9 – Benchmark Thermal Boundary (Second Floor)

The second floor thermal boundary includes the apartment units and the staircase lobby. The rose window on the east façade is included in the thermal boundary. It is part of the community room.

Figure 10 – Benchmark Thermal Boundary (Section)

The basement and attic are unconditioned and not included in the thermal boundary. The conditioned floor area is 11577sq.ft. The conditioned volume is 115770 cu.ft.

4.2 Assemblies The schematic details received from the architect indicate that the Rockwool batts have been proposed for insulation material. The type of construction (standard, advanced) has not been indicated for all assemblies. Several assumptions have been made to detail the assemblies for the benchmark case. They have been specified as required.


4.2.1

Ceiling

The benchmark case has three layers of 5.5” Rockwool batts placed one over the other. Thebatts are placed with their fibersin opposite directions. This helps reduce the air flow through the batts. The batts have been placed over a suspended Chicago grid ceiling. The Rockwool batts have been substituted with mineral fiber batts as they have a higher R-value per inch as compared to rockwool2. The framing factor for the Chicago grid has been assumed to be zero due to comparatively low surface area it takes up.

Type

Benchmark Retrofit - Cavity (used for modeling) R-Value (per R-Value (total) inches inch) ft2.F.h/BTU

Outside Air Film Rock Wool (Batt) Rock Wool (Batt) Rock Wool (Batt) Chicago grid frame for suspended ceiling Gypsum white board Inside Air Film

5.5 5.5 5.5 N/A 0. 62 -

Thickness

16.5”

3 3 3

R-Value

Type

50.89 Benchmark Retrofit – Cavity (Modified) R-Value (per inches inch)

Outside Air Film Mineral Fiber (5.5" Batt) Mineral Fiber (5.5" Batt) Mineral Fiber (5.5" Batt) Chicago grid frame for suspended ceiling Gypsum white board Inside Air Film

5.5 5.5 5.5 N/A 0.62 -

Thickness

16.5”

R-Value

2

0.68 16.5 16.5 16.5 N/A 0.56 0.15

Values taken from REM/Rate which uses ASHRAE Fundamentals 1997 values

n/a n/a n/a

R-Value (total) ft2.F.h/BTU 0.68 19 19 19 N/A 0.56 0.15 58.39


Figure 11- Modified benchmark ceiling cavity section

Insulation: Mineralfiber Batts Construction: Chicago Suspended Ceiling Cavity R-Value: 58.39 ft2.F.h/BTU Framing R-Value: Framing Factor: 0% Overall R-Value: 58.39 ft2.F.h/BTU Overall U-Value: 0.017 BTU/h °F ft² Thickness of Section: 16.5 ” 4.2.2

On Grade Walls - External

The benchmark case has insulation of 2 layers of 5.5” Rockwool batts. However, only one 1.5” x 5.5” stud wall at 16 o/c has been indicated. It is proposed that this assembly be modified to include two double stud walls with 1.5” x 5.5” @ 16 o/c. The double stud walls can be separated by a 2” layer of batt insulation. This will help increase the R-value of the value and will also reduce the thermal bridging. By adding a 2” layer of batt in between with its grains in the opposite direction, the air tightness of the assembly will increase. The framing factor for this wall be zero as there is no thermal bridging (Straube & Smegal, 2009). This wall will also be easy to construct as the laborers are already well-trained in construction of wood stud + batt insulation walls. It is suggested that the Rockwool be replaced with Mineralfibre batts. It is assumed that a 1” air gap will be provided between the masonry wall and the wood stud wall to allow drainage of moisture from the wall section through flashing. This is essential in an old masonry construction fitted with interior insulation. As the interior drying capacity of the wall is reduced, it is essential to provide details to remove the ascending moisture or the wall will deteriorate and it could lead to mold problems.

Benchmark Retrofit - Cavity (used for modeling) Type

Outside Air Film Solid Brick air-gap Rockwool(Batt) 2" Rockwool In between Rockwool (Batt) Gypsum White Board Inside Air Film Thickness

inches

16 1 5.5 2 5.5 0.625 30.625

R-Value (per inch)

0.1 3 3 3

R-Value (total) ft2.F.h/BTU 0.17 1.6 1 16.5 6 16.5 0.56 0.68


R-Value

42.84

Benchmark Retrofit - Cavity (Modified) R-Value inches (per inch)

Type Outside Air Film Solid Brick Air-gap Mineralfibre (Batt) 3" Mineralfibre Inbetween (batt) Mineralfibre (Batt) Gypsum White Board Inside Air Film Thickness R-Value

16 1 5.5 3 5.5 0.625

0.1

R-Value (total) ft2.F.h/BTU 0.17 1.6 1 19 11 19 0.56 0.68

31.625 52.84

Figure 12 –Modified benchmark on-grade wall plan

Insulation: Mineralwool Batts (replace Rockwool batts) Construction: 1.5”x5.5” wood studs @ 16” o/c, double wall Cavity R-Value: 52.84 ft2.F.h/BTU Framing R-Value: 7.215 ft2.F.h/BTU Framing Factor: 0% Overall R-Value: 43.47 ft2.F.h/BTU Overall U-Value: 0.023 BTU/h °F ft² Thickness of Section: 31.625” 4.2.3

Floors

Retrofit of the existing frame floor (between the first floor and basement has been proposed. Carpet floor with a plywood sub-floor are proposed. It is proposed that 3.5” of sound insulation batt be filled in the 9.5” deep joist cavity. The frame floor is to be covered with 5/8” Gypsum white board. Sound insulation is assumed to be fiberwool batt insulation as it is the most commonly used sound insulation. Benchmark Retrofit - Cavity


Type

inches

Inside Air Film Carpet with rubber pad Plywood Sound Insulation (Fiberwool Batt) G.W.B Outside Air Film

1 0.5 3.5 0.6

Thickness

5.6

R-Value (per inch)

R-Value (total) ft2.F.h/BTU

-

0.68 1.23 0.62 11 0.56 0.17

R-Value

12.18

Figure 13 – Benchmark Frame Floor Section

Insulation: Fibrewool Batts Construction: 1.5”x9.5” wood joists @ 16” o/c, standard framing Cavity R-Value: 12.18 ft2.F.h/BTU Framing R-Value: 14.28 ft2.F.h/BTU Framing Factor: 13%3 Overall R-Value: 15.38 ft2.F.h/BTU Overall U-Value: 0.065 BTU/h °F ft² Thickness of Section: 27.12” 4.2.4

Basement

It is mentioned that a 1.5” x 3.5” @ 16” o/c standard wood stud wall construction shall be used. 5.5” Rockwool batts are mentioned. It is assumed that 3.5” Rockwool batt will be installed in the wood stud cavity and 2” Rockwall batt will be stapled to the frame. It is suggested that the Rockwool be replaced with Mineralfibre batts. A 1” air gap to drain moisture is accounted for.

Benchmark Retrofit - Cavity Type Solid Brick Air gap Rock Wool (Batt) 3

inches

R-Value (per inch) 20 1 5.5

Values taken from REM/Rate which uses ASHRAE Fundamentals 1997 values

R-Value (total) 0.1 3

2 1 16.5


Gypsum White Board Thickness R-Value

0.62 27.12

0.56 20.06

Figure 14 – Benchmark basement wall

Insulation: Mineralwool Batts ( replace rockwool batts) Construction: 1.5”x3.5” wood studs @ 16” o/c, standard framing Cavity R-Value: 20.06 ft2.F.h/BTU Framing R-Value: 9.435 ft2.F.h/BTU Framing Factor: 13% Overall R-Value: 16.50 ft2.F.h/BTU Overall U-Value: 0.060 BTU/h °F ft² Thickness of Section: 27.12” 4.2.5   

Windows Total Window Area – 1361sq.ft Window to Wall Ratio (whole building)– 0.178 Window to Floor Ratio (whole building) – 0.118

Window orientation – Windows are oriented along the north and south façade. The housing units are along these two facades. The original windows are divided into two parts to accommodate for the second floor addition at mezzanine level. The window size is further reduced due to addition of window sills. The average window area in each typical unit is 67.5 sq.ft. There are no windows along the west façade. There is a large rose window on the east façade which lights up the common hall on the second floor. The newly added lobby has glass curtain walls along the south and east façade. As the thermal boundary includes the lobby and community hall, it is necessary to ensure that glazing and window assemblies with sufficiently low U-values are used to reduce heat loss through the windows. The window model selected is manufactured by Serious Windows. It is from the SeriousWindows 925 Series. The Serious Glass 9H package has been used. These windows are designed to have high R-values and high passive solar heat gain as required by northern climates. Casement windows have been selected for the unit windows and picture windows have been selected for the rose and round windows on the north, south and east facades. It is assumed that the windows will be manufactured as per building opening requirements. Only the R-values of the windows were provided in the schematic drawings. The provided R-Value was 7. The windows suggested for the model fulfill Passivhaus requirements. Technical Specifications4 4

Serious Windows 925 Series


Window Type Casement Picture Cost - ~ 60 sq.ft5

U-Value BTU/h °F ft² 0.16 0.12

R-Value ft2.F.h/BTU 6.3 8.3

SHGC

VT

0.41 0.32

0.53 0.41

Figure 15 – Window Detail

SeriousWindows 925 is a triple glazed window with inert gas fill. It has a fully insulated, high strength and low conductive fiberglass frame. The window is three times more efficient than Energy Star standards. It has 99.5% UV protection and is highly resistant to condensation preventing mould and IAQ problems. It has a superior strength to weight ratio, making it ideal for large window openings such as the rose window. 4.2.6

Doors

The main door of the building is facing the south. There are no other doors to the building. The door selected for the church is Energy Star rated. The selected doors are manufactured by ThermaTru. The door has a R-value of 6.25 ft2.F.h/BTU. 4.2.7 Assumptions for Lobby and Staircase Extension No assembly details were provided for the staircase and lobby extension. The following assumptions were made – On-Grade Wall Type Outside Air Film Brick Veneer Polyisocyanurate Board Plywood Wood Studs Rock Wool Gypsum White Board 5

Ceiling

R-Value (total) ft2.F.h/BTU 0.17 0.4 12.5 0.77 6.8750 33 0.56

Type Outside Air Film 4” Rigid Insulation Plywood Open Cell Spray Foam Rock Wool Wood Studs Gypsum White Board

Cost of Serious Windows 725 Series as unable to find cost of 925 series

R-Value (total) ft2.F.h/BTU 0.17 25 0.77 5.25 16.5 6.875 0.56


Inside Air Film Total R-Value

0.68 42.84

Inside Air Film Total R-Value

0.68 55.035

Assemblies with R-Values similar to the proposed benchmark retrofit are assumed for the basement walls. 4.2.8

Considerations:

Moisture Control - Providing a permeable insulating assembly may not be the best option for moisture control while retrofitting old masonry buildings. If not detailed and constructed properly, moisture may collect on the interior insulation surfaces leading to mold and mildew problems.

Air Tightness – The current assembly may not provide the air tightness levels required by Passivhaus.

Quality (Grade) of Construction – Batt insulation installation is cumbersome as compared to other assembly construction. There is a high possibility of having gaps in the assembly. Hence, Grade 1 quality of construction may be difficult to achieve.

Rockwool Thermal Performance – Rockwool has a lower thermal performance as compared to most other insulation materials including mineral wool.

Insufficient Insulation at Frame Floor – The R-value of the frame floor insulation may not sufficient to reach Passivhaus standards of heating demand.

Insufficient Support at Ceiling – Provision of only a Chicago grid ceiling may not be enough to support equipment or laborers when they need to access to attic for maintenance work.


4.3 Building Systems 4.3.1

Domestic Hot Water

In line with the desires of the owner/developer, the benchmark model of this building also used solar powered domestic hot water. We assumed an individual hot water storage tank and collector area for the baseline model. This results in 15 80 gallon tanks- 1 per unit and 1 per common area including the laundry. This resulted in an overall collector area of 1,200 sq. ft. of flat panel collectors and 15 80 gallon tanks for a total capacity of 1,200 gallons. All of the tanks are Energy Star rated because they fall within the residential sizing range that Energy Star covers. 4.3.2

Heating / Cooling

For the baseline model, we assumed air to air heat pumps- 1 for the common space and 1 per 2 units. Using rule of thumb sizing strategies, we estimated that a one ton unit could service 500 – 600 sq. ft. of conditioned floor area. This results in 7 2-ton heat pump units for the apartments and about a 4 ton unit for the common areas. Air to air systems are much less efficient than hydronic systems and typically have coefficients of performance well below those that are water-based. In addition one component of the air to air heat pumps is located outdoors. Given the site restrictions at St. Mary’s this solution may be less than ideal. Also with the indoor component of the heat pump located in unconditioned floor area, additionally efficiencies would be lost.

[7]


4.3.3

Ventilation

A centralized energy recovery ventilation system was chosen for the baseline model that served the capacity needed for the entire building. ERVs are standard, accepted pieces of equipment in most passive house designs because of their ability to provide superior indoor air quality through natural ventilation, recapture waste heat from the system for maximum efficiency, and their ability to reduce latent moisture in supply air. Due to the capacity needed for the centralized system, a larger unit had to be selected which results in system that consumes more electrical energy than a distributed system as modeled in our proposed model.

4.3.4

Electricity

The owner and developer did not mention the integration of a solar photovoltaic or other renewable energy generation source as this project was not intended to net to zero energy consumption- site or source. Because of this, we decided not to model a net zero system as we did in our proposed building model. 4.3.5

Appliances & Lighting

For the baseline scheme, we used the same high-performing appliances as modeled in our proposed model. More information about these appliances is located toward the end of this report.


4.4 Site / Source Energy Spreadsheet

Because the heating and cooling energy consumption in the baseline model is higher than our proposed model, this result in a large energy consumption load and a higher site energy use intensity than the proposed solution. This energy balance spreadsheet also uses the default values used for lighting and appliances that the software generates to create a HERS index score. Despite this, the site energy use intensity is quite low for a multifamily housing project of this scale, which is a testament to the good building envelope suggestions in place in the existing scheme. Comparatively, the site EUI score for a typical single family residence is 44, so this score is quite good.


4.5 Compliance 4.5.1

IECC 2012 Guidelines

As anticipated, even the baseline model is a good performer and easily complies with IECC 2012.


4.5.2

HERS Rating Index

4.5.3

URA Guidelines

Guidelines for building energy efficient homes with the Urban Redevelopment Authority of Pittsburgh (URA) Compliance to Energy Star for New Homes Program – Version 3 Refer to Energy Star Checklist

Compliance to Indoor airPLUS / Water Management Builder and Rater Checklists from ENERGY STAR Moisture Control Proper drainage of bulk water away from home Proper layering of drainage plane Proper flashing around windows, doors, gutter, roof intersections Radon Control Perforated under slab piping Continuous and sealed under slab vapor barrier (6-mil polyethylene) Internal pipe venting through roof of unit


junInstallation of junction box adjacent to attic piping Access to attic through attic hatch HVAC Manual J load calculations Use ‘Tight’ under construction quality in Infiltration Section using Simplified Calculation Method Ductwork Sized according to ACCA Manual D, ASHRAE Handbooks All supply, return paths fully ducted All seams and joints sealed with UL-181 No ductwork and mechanical equipment in garage spaces Continuous Ventilation ENERGY STAR rated bath fan with a motion sensor, variable speed control for continuous operation in one upstairs bathroom - Final ventilation rate set after performance testing of air tightness of the building envelope - Following fans qualify – Panasonic WhisperGreen Ventilation Fans Local Exhaust Ventilation Kitchenhoods, bath fans, clothes dryers ducted to outdoors Shortest length of ductwork used All ductwork minimum 4” in dia All local ductwork in rigid sheet metal Seams sealed with UL-181 Ductwork insulation covered with a vapor barrier to prevent condensation Low Emitting Materials Low-emitting materials – ‘off-gas’ harmful chemical like VOC’s and formaldehyde - Certified low-formaldehyde pressed wood materials used (i.e., plywood, OSB, MDF, cabinetry) - Certified low-VOC or no-VOC interior paints & finishes used - Carpet, adhesives, & cushion qualify for CRI Green Label Plus or Green Label testing program

Although this design meets the basic URA requirements, one area of concern is the location of all the mechanical equipment in the unconditioned basement area. Although none of the equipment is technically placed within a garage area, the location of major equipment in unconditioned spaces is certainly undesirable and will reduce overall systems efficiency. Additionally the insulation “sealing” of the ceiling in the proposed scheme would make maintenance of roof pipe venting and junction box maintenance extremely difficult not to mention repairing roof leaks. 4.5.4

Energy Star Guidelines

Energy Star Qualified Homes National Attached Homes for BOP Requirements Pittsburgh – Climate Zone 5 (prescriptive path requirements) Energy Star HERS Index target = HERS Index of Energy Star Reference Design x SAF -

For apartments in multi-family buildings

SAF = 1 (as specified) Energy Star HERS Index target = HERS Index of Energy Star Reference Design x SAF


-

For whole building (detached homes more than 8 bedrooms)

CFA = (600 x 14) + 400 = 8800 sq.ft

Minimum Building Envelope Requirements – Grade I Installation (IP Units as applicable) ☒ ☒

Wood Frame Floor over unconditioned spaces Assembly U-Factor = 0.033 Above Grade Walls Solar Absorptance = 0.75 Emittance = 0.90 Assembly U-Factor = 0.057 Opaque Doors Assembly U-Factor = 0.21 SHGC = N/A Glazing Total Area = 15% of conditioned floor area6 Orientation = Equal distribution on all facades Internal Shade Co-efficient = RESNET Standard External Shading = None Assembly U-Factor = 0.30 SHGC = 0.40 Wood Frame Ceilings Assembly U-Factor

Minimum Heating System Requirements 90 AFUE Gas Furnace 85 AFUE Oil Furnace 85 AFUE Gas/Oil Boiler 9.25 HSPF/ 14.5 SEER/ 12 EER Air-Source Heat Pump Electric Air-Source Heat Pump Back-up

Minimum Cooling System Requirements 13 SEER AC 14.5 SEER Air-Source Heat Pump

Minimum Service Water Heating System Requirements

☒ ☒

6

Gallons per day Tank Temperature Gas Storage Tank Capacity 0.63 EF 30 Gallon Tank 0.61 EF 40 Gallon Tank 0.59 EF 50 Gallon Tank 0.57 EF 60 Gallon Tank 0.55 EF 70 Gallon Tank 0.53 EF 80 Gallon Tank Electric Storage Tank Capacity 0.94 EF 30 Gallon Tank 0.93 EF 40 Gallon Tank 0.92 EF 50 Gallon Tank 0.91 EF 60 Gallon Tank 0.90 EF 70 Gallon Tank

If window-wall ratio (WFA) > 15%, Improved U-Value = (0.15/WFA) x Energy Star U-Value


0.89 EF 80 Gallon Tank For additional tank sizes Gas DHW EF ≥ 0.69 – (0.002 x tank gallon capacity) Electric DHW EF ≥ 0.97 – (0.001 x tank gallon capacity) Oil DHW EF ≥ 0.61 – (0.002 x tank gallon capacity)

Minimum Thermal Distribution System Requirements ☒ ☒

Duct leakage to outdoors ≤ 4 CFM25 per 100 sq.ft of conditioned floor area Total duct leakage ≤ 6 CFM25 per 100 sq.ft of conditioned floor area R-8 duct insulation in unconditioned attic R-6 duct insulation in all other unconditioned spaces Supply and return duct locations for basement type foundation in two story building - 50% Attic -

50% Basement

Thermostat Requirements ☒ ☒

Programmable Thermostat Temperature Set-Points

Infiltration and Mechanical Ventilation System Requirements ☒ ☒

4 ACH50 Infiltration Rate Mechanical ventilation system without heat recovery - Rate: CFM=0.01 x CFA7 +7.5 x (NBr8 + 1) -

24 hours running

-

Fan Watts: Watts = CFM Rate/2.2 CFM per Watt

Exhaust Ventilation

Lighting, Appliances and Internal Gains Requirements ☒ ☒

80% Fluorescent Lighting 423 kWh per year Refrigerator 0.66 EF Dishwasher 122 CFM/Watt Ceiling Fan Energy Star qualified refrigerators, dishwashers, ceiling fans, exhaust fans, CFLs, LEDs, pin-lighting Internal gains

Internal Mass ☒

Internal mass

The areas highlighted in yellow show non-compliance. Given the sizing restrictions of the equipment, it was difficult to find equipment meeting the minimum efficiency requirements. As this example shows, it is incumbent on the mechanical engineer to select the highest performing equipment to meet Energy Star 3.0 compliance, which may result in under or over-sizing. The strategy of sizing equipment to the peak load may not result in equipment that meet Energy Star’s high efficiency standards. In this scheme since all of the

7 8

CFA – Conditioned Floor Area NBr – Number of Bedrooms


mechanical equipment in this scheme is located in the unconditioned basement, to meet the Energy Star requirements, this requires extra insulation around ductwork, which is both labor-intense and costly.


5 Analysis of Proposed Retrofit Design 5.1 Thermal Boundary Location

Figure 16 – Benchmark Thermal Boundary (First Floor)

The thermal boundary has been modified. It does not include the staircase and entrance lobby. This will help increase air tightness of the building, an important criteria for Passivehaus design. Heatloss through the curtain-walled entrance lobby will also be minimised. As it is a circulation space, it is assumed that the residents will not spend a lot of time in this space. Hence, it is a reasonable decision to reduce the thermal boundary of the building.

Figure 17 – Benchmark Thermal Boundary (Second Floor)

The thermal boundary of the second floor was also modified to exclude the staircase lobby.


Figure 18 – Benchmark Thermal Boundary (Section)

The basement and attic are unconditioned and not included in the thermal boundary. The conditioned floor area is 10752 sq.ft. The conditioned volume for is 107520 sq.ft.

5.2 Assemblies New assemblies have been proposed. This includes suggestions for insulation as well as framing. The R-walls for most of the existing assemblies are already high. They are similar to the Passivhaus thumbrules for assembly design. As per Passivhaus, the ceiling should have a R-value of 60 ft2.F.h/BTU, the on-grade external walls should have a R-value of 40 ft2.F.h/BTU, the Frame Floor should have R-value of 20 ft2.F.h/BTU and window and doors should have R-value of 7 ft2.F.h/BTU. The benchmark assemblies have the following R-values –      

Ceiling- 58.39 ft2.F.h/BTU On-grade external wall – 42.84 ft2.F.h/BTU Frame Floor – 12.18 ft2.F.h/BTU Basement Wall- 20 ft2.F.h/BTU Window – 6.3-8.3 ft2.F.h/BTU Door – 7 ft2.F.h/BTU

Insulation Materials: Loose-fill fiberglass by JM Spider and closed cell polyurethane spray foam by Honeywell are proposed for insulation. Both materials have been selected due to their properties to act as air and vapor barriers. Both materials have a high R-value per inch which enable us to get a high R-Value wall with a less thick assembly. The R-values for Spiderglass are taken from manufacturer’s specifications. The R-value for closed cell polyurethane are taken from the REM/Rate library.


The URA guidelines which mandate compliance to IndoorPLUS require that materials used for construction are non-toxic to maintain good indoor air quality. This has been considered when suggesting materials. It is also easier to install these insulation materials as compared to batts. This will help achieve Grade I quality of construction which is a mandatory requirement for Energy Star v3 and Passivhaus compliance.

Blown-in Fiberglass Blow in Spiderglass insulation is formaldehyde-free fiber glass insulation. It provides upto 30% better airflow resistance as compared to lose fill cellulose. Fiber-glass is also naturally mold resistant and has a high Rvalue per inch. In addition, an adhesive binder is used in manufacturing this fiber-glass insulation. This prevents settling of the insulation material and helps maintain a uniform high R-value for the entire assembly. Use of the adhesive binder does not change the properties of the fiberglass. This insulation works well for fire resistance too.

Closed-Cell Polyurethane Spray-in Foam Closed cell polyurethane foam has a high structural strength, good air infiltration control, good moisture/condensation control and a high thermal insulation (R-value per inch). As a result, it helps improve energy savings and improve indoor comfort by reducing drafts. It also increases the structural strength of the assembly as it does not warp or settle down like most other insulation materials. The properties of foam which help it act as a vapor and air barrier along with its ability to fit into small, difficult to reach cavities make it an ideal selection to insulate the thick masonry walls of the church. There are some reservations for using closed-cell polyurethane foam as usually this material is made using HFC-245fa which has a high Global Warming Potential (GWP) of 1030. However, closed cell spray foam manufactured by Honeywell has been proposed for the retrofit. Honeywell uses an advanced blowing agent technology Enovate® 245fa. Enovate® 245fa uses a hydrofluorocarbon that is zero-ozone depleting and nonflammable. Hence, even though closed cell spray foam has a higher cost, it has a much better value. Advanced Framing Reduction of thermal bridging is essential to attain Passivhaus standards. Hence, use of advanced framing has been proposed for the assemblies. In addition to reducing thermal bridging (it has a lower framing factor), advanced framing will also help reduce the quantity of wood used for construction (Straube & Smegal, 2009). REM/Rate framing factors for advanced framing have been used for R-Value calculations. As double stud 8” staggered wall is proposed for the external walls as this construction not only helps eliminate thermal bridging, but also helps increase the cavity depth for insulation installation. This will help attain a higher R-value for the wall assembly. 5.2.1

Ceiling

A 1.5” x 5.5” wood stud frame roof @ 24 o/c with advanced frame construction is proposed. Closed cell spray foam (3.5”) is installed as a wash at the base. Loose-fill Spiderglass is filled on top to attain the required Rvalue. Use of these two materials helps reduce cost of assembly and also maximizes use of polyurethane foam to the best of its properties (the thermal performance of polyurethane foam reduces beyond a thickness of 3.5”).


Type Blown-in Fibreglass Blown-in Fibreglass Closed cell foam Gyp board Thickness

Proposed Retrofit – Cavity RValue (per R-Value (total) inches inch) ft2.F.h/BTU 4 10 2 0.62

6

15 38 12 0.56

16.62

R-value

65.56

Figure 19 – Proposed ceiling cavity retrofit

Insulation: JM Spiderglass* + Honeywell Closed cell polyurethane foam ** Construction: 1.5”x5.5” wood studs @ 24” o/c, Advanced Framing Cavity R-Value: 65.56 ft2.F.h/BTU Framing R-Value: 5.4 ft2.F.h/BTU Framing Factor: 9% Overall R-Value: 66.66 ft2.F.h/BTU Overall U-Value: 0.015 BTU/h °F ft²


5.2.2

On-Grade External Walls

The exterior walls are coated with closed-cell polyurethane foam internally. This is directly applied to the brick. The foam acts as a vapor and air barrier and prevent the wall from drying to the interiors. A 1.5” x 3.5” @ 16” o/c staggered wall with 8” depth is proposed. This wall is ties to the brick wall at a distance of 2”. The 2” gap allows the spray to be filled in properly and also provides a uniform leveled surface for assembly installation (the surface of masonry brick wall is uneven and it will be difficult to build the insulation assembly flush against it). Flashing needs to be provided at all necessary joints to allow for moisture drainage. Proposed Retrofit - Cavity R-Value (per inches inch)

Type Outside Air Film Solid Brick Closed cell polyurethane foam Spiderglass Dry wall-Gypsum board Inside Air Film Thickness R-Value

16 2 8 0.62

R-Value (total) ft2.F.h/BTU 0.17 0.1 1.6 6 12 30 0.56 0.68

26.62 44.84


Figure 20 – Proposed external on-grade wall retrofit (plan)

Figure 21 - Proposed external on-grade wall retrofit (cavity)

Insulation: JM Spiderglass* + Honeywell Closed cell polyurethane foam ** Construction: 1.5”x3.5” wood studs @ 16” o/c, staggered wall, 2” ties Cavity R-Value: 44.84 ft2.F.h/BTU Framing R-Value: 7.215 ft2.F.h/BTU Framing Factor: 0% Overall R-Value: 43.45 ft2.F.h/BTU Overall U-Value: 0.022 BTU/h °F ft² 5.2.3

Frame Floor (between unconditioned basement and conditioned first floor)

The insulation has been increased at the frame floor. 2” closed cell spray foam is sprayed on the underside of the floor in between the joists. The remaining cavity is filled with loose-fill Spiderglass. Proposed Retrofit - Cavity

Type Hardwood Plywood

R-Value inches (per inch) 0.75 0.5

R-Value (total) ft2.F.h/BTU 0.7 0.62


Closed cell spray foam Spiderglass Gyp board Thickness

Proposed Retrofit - Cavity 2 3 9.5 0.62

6 38 0.56

13.37

R-Value

45.88

Figure 22 – Proposed frame floor retrofit

Insulation: JM Spiderglass* + Honeywell Closed cell polyurethane foam ** Construction: 1.5”x9.5” wood studs @ 16” o/c, Standard Framing Cavity R-Value: 39.88 ft2.F.h/BTU Framing R-Value: 9.03 ft2.F.h/BTU Framing Factor: 13% Overall R-Value: 33.33 ft2.F.h/BTU Overall U-Value: 0.030BTU/h °F ft² Closed-cell spray cell foam is also applied to the interior of the joist cavities at the rim and band joist. This helps increase the R-value at the rim and band joist. This is essential as there is a lot of heat loss at this junction. It is allowed to have exposed closed cell-spray foam for up to 3.5” as per International Residential Code (IRC) guidelines. The gap between the rim joist and the masonry wall is also filled in with the foam. This helps reduce thermal bridging as the closed-cell spray foam acts as a continuous insulation layer.


Figure 23 – Proposed rim and band joist retrofit

5.2.4

Basement

Basement Wall Assembly A 1.5” x 3.5” wood stud wall @ 24” o/c with advanced framing is proposed. The wood stud wall is separated from the masonry wall by 2”. The 2” gap is filled with closed cell spray foam. The wodd stud wall has loose fill Spiderglass insulation. Even though the basement is not conditioned, it has been insulates as mechanical equipment for the service systems will be placed in the basement. The insulation will help moderate the thermal conditions in the basement. Proposed Retrofit -Cavity Type

inches

R-Value (per inch)

Solid brick Closed cell foam Jm spiderglass*

20 2 3.5

Dry wall-gypsum board

0.62

Thickness R-Value

0.1 6

R-Value (total) ft2.F.h/BTU 2 12 15 0.56

26.12 29.56


Insulation: JM Spiderglass* + Honeywell Closed cell polyurethane foam ** Construction: 1.5”x3.5” wood studs @ 24” o/c, staggered wall, 2” ties Cavity R-Value: 29.56 ft2.F.h/BTU Framing R-Value: 6.95 ft2.F.h/BTU Framing Factor: 9% Overall R-Value: 27 ft2.F.h/BTU Overall U-Value: 0.037 BTU/h °F ft²

Basement Slab It is proposed that the new slabs that are laid in the basement are well insulated and provided with radon control measures. Polyisocyanurate board has been suggested as it has a lower GWP as compared to polyurethane boards and has a higher thermal performance. Proposed Retrofit

Type Linoleum Plywood Concrete slab (normal weight) Polyisocyanurate Board Air and Water barrier-6mil polyethylene Coarse Gravel base (with air gaps) Thickness R-Value

inches 0.13 0.5 4 6 12

R-Value (total) ft2.F.h/BTU 0.05 0.62 0.08 0.32 6.25 37.5 0 0.09 1.08

R-Value (per inch)

10.5 38.44

Measures for Radon Mitigation (IndoorPLUS compliance)    

Use of Gravel under slab to allow gas to flow freely under slab itself Provide vent pipe from roof to gravel to maintain negative pressure under slab Provide warning system Provide an air and water barrier to prevent moisture and radon to rise up into the basement


Source - http://www.indoor-air-health-advisor.com

Figure 24 – Radon Mitigation System

5.2.5

Windows

Same as previous model

5.2.6

Doors

Same as previous model


5.3 Building Systems

Diagram of Integrated Building Systems 5.3.1

Heating / Cooling

For the building’s heating and cooling system, we employed a California Loop system. A California Loop is a hydronic heating and cooling system that uses a combination of equipment including water source heat pumps, a backup heat source (necessary for cold climates), a heat sink to exhaust excess heat, and a closed water loop maintained at a specific temperature depending on whether the system is in heating or cooling mode. We believed that a hydronic system might prove the most efficient since “one cubic foot of water can store or transfer the same amount of heat as over 3,000 cubic feet of air” [3]. With the added efficiency of a hydronic system, we believed that we would come closer to achieving net zero and passive house standards than with a conventional air-based system.


In a water-loop heat pump system zones may be heated or cooled by an individual water to air heat pump. Thermostats in each zone “determine whether the local heat pump extracts heat from the water loop (heating mode) or injects heat into the water loop (cooling mode)” [2]. According to Lechner, “the water-loop heat-pump system really shines in spring and fall or whenever about half the heat pumps are in the cooling mode and the other half are in the heating mode. In that case, the heat extracted from the water loop will roughly equal the heat injected, and neither [evaporative condenser] nor boiler needs to operate” [2]. This is particularly relevant to our building which experiences significant heat gain on the south façade in both summer and winter and significant shading on the north façade in all seasons. By using a zoned hydronic system, the heat pumps have the capacity to simultaneously cool or heat in disparate zones depending on the temperature desired. Typically during summer months, the water to air heat pumps reversing valves operating in cooling mode and exhaust waste heat into a heat sink [2]. In our configuration, we are employing an evaporative condenser as the heat sink because of site restrictions that preclude the use of a geothermal system that would use the ground as a heat sink. In most systems that do not employ a geothermal system, the heat sink consists of a cooling tower. We chose an evaporative condenser as a heat sink because we were unable to find a cooling tower sized small enough to handle the very low loading required to operate as a heat sink (approximately 50% of our cooling load) and because of higher efficiencies associated with this type of equipment. To maintain a consistent temperature in the water loop in winter, the California Loop requires a backup heating system, particularly in heating dominated climates such as Pittsburgh. In addition to desuperheaters that capture waste heat from our heat pumps, a backup boiler sized at ½ of the heating load was chosen as the backup heating system. The boiler system chosen has the added benefit of serving as the backup heating system for the domestic hot water system as well and will be discussed later in this report. A diagram of this system is included below:

5.3.2

Water to Air Heat Pumps


Because our project is considered multifamily housing, we anticipated economies of scale to be experience in sizing shared mechanical equipment such as the boiler and the evaporative condenser. According the Energy Star guidelines, each unit requires individual control over their heating and cooling. As such, we chose high efficiency ½ ton water to air heat pumps for each unit and a larger, central heat pump sized for the floor are of the common areas located on the first and second floors. Due to the small sizing of the individual units’ heat pumps, these pieces of equipment can easily fit in a closet space within the individual unit for convenience and also to maintain location within the conditioned floor for maximum efficiency. The table below shows the sizing strategy for heat pump selection, which are all electrically powered.

The specification sheets included with this report contain more specific information regarding the equipment selections. Both types of heat pump were chosen based on their ability to meet both the peak heating and cooling loads and their efficiencies. The individual unit heat pumps maintain a coefficient of performance of 4.8 whereas the common are heat pump has a coefficient of performance of 6.1. The measure is a ratio of energy input to energy output, higher is better. From these ratios alone, we can see the inherent efficiencies of a water-based system over a traditional air-based system. A sample of the spec information is shown below for the heat pumps for individual units:


5.3.3

Back-up Boiler System

As a backup heating system the boiler does need to be sized to meet peak load in a water-loop heat pump system. A departure from our other mechanical equipment, the boiler uses natural gas as its heat source. Natural gas boilers are one the primary type that not only meet Energy Star requirements but also have optimal operating efficiencies. Our sizing methodology is listed below:


Because we were able to size a smaller-capacity boiler, not only did our specified boiler achieve AHRI certification, but it also achieved an Energy Star rating. Specifications on this piece of equipment are located at the end of this presentation. Although small in profile, the boiler is slated for placement in the unconditioned basement. This is perhaps the primary reason our proposed design did not achieve Energy Star 3.0. 5.3.4

Heat Sink – Evaporative Condenser

Although almost all of our system components achieved an AHRI certification, evaporative condensers are currently outside the scope of AHRI’s certification process. Additionally, most evaporative condensers are seen in commercial applications and rarely in residential construction. We incurred challenges finding an evaporative condenser small enough to meet the loads necessary for back-up cooling and reduce energy consumption. We were able to find a suitable piece of equipment that more than satisfied our need for a heat sink. Any heat sinkground, cooling tower, or evaporative condensers- is usually located in ambient conditions outside. Heat sinks typically also require placement at a sufficient height above the remaining equipment to exhaust waste heat to the outside. We chose to place the evaporative condenser in the church steeple because of its sizing, higher vertical orientation relative to the other pieces of equipment, to purpose currently unusable space, and because with replacement louvres to the church steeple, it is simply the most aesthetically ideal and covert solution. A diagram showing this location particularly in relation to our other systems is included later in the report. With a peak cooling load of about 47.0 kBtu/hr, the specified equipment more than meets our base heat rejection requirements. Some information regarding our evaporative condenser selection is shown below:


5.3.5

Systems Case Study: The Sawmill Building, Lincoln, Nebraska

[5] To support our design decision for the California Loop system, we analyzed a similar case study as a benchmark for comparison. The Sawmill Building in Lincoln, Nebraska built in 1910 proved the most relevant example to compare against our building. Similar to Pittsburgh, Lincoln has a heating dominated climate. Similar to the St. Mary Street Apartments, the Sawmill building was an adaptive reuse of a historical masonry structure, albeit for a commercial program rather than residential. The building features a closed hydronic system with water loop heat pumps with zoned controls similar to our proposal. A LEED certified building, the Sawmill Building did not attempt to meet Passive House, Energy Star 3.0, IECC 2012, or net zero energy consumption. The building experiences better economies of scale because of its larger floor area and larger respective zone as they serve a commercial function as opposed to a residential one. Not only was this mechanical system successful, the Sawmill Building has been transformed into a beacon within its community and a public educational tool on sustainable building and mechanical system best practices. [4] 5.3.6

Benefits & Drawbacks of the California Loop Mechanical System

System Benefits: Economies of Scale for shared system components (i.e. boiler, ERV, evaporative condenser) High Efficiencies and Performance Hydronic Systems - 1 cubic foot of water transfers the same amount of heat as over 3,000 cubic feet of air Limited amount of duct work Smaller profile piping for hydronic systems Most system components located within conditioned space Individual unit control over heating and cooling Recapture of Waste Heat and Cooling

System Drawbacks:


Mostly for commercial applications Potential oversizing of equipment Innovative & Unconventional Requires savvy HVAC engineer Potential higher expenses Requires more skilled Operations & Maintenance workers 5.3.7

Ventilation

Ventilation for the building was best accomplished by using an energy recovery ventilation system. ERVs are standard, accepted pieces of equipment in most passive house designs because of their ability to provide superior indoor air quality through natural ventilation, recapture waste heat from the system for maximum efficiency, and their ability to reduce latent moisture in supply air. Because air supply to distribution temperatures are within reasonable tolerances as are humidity levels in ambient air, the energy recovery ventilation system is well suited to the Pittsburgh climate as well as our project. A series of optimal sizing conditions were explored to find the most efficient system configuration. We attempted sizing a single ERV for each unit with one large unit for the common areas, having 2 or 3 units sharing an ERV, or using a more centralized system by having 1 ERV for all 14 units and another unit for common spaces. The last option proved the most efficient in terms of sizing and prevented gross oversizing of the ERV units. Given the sizing of the ERV units selected, we were able to place the units within the dropped ceiling plenum of the building corridor. By placing the units in conditioned area and thus having our air ducting within conditioned area, we were able to avoid the IECC 2012 requirement to have to insulate ductwork with a minimum of R-6 for a ductwork occurring in unconditioned space as in the baseline scheme. This not only maximized overall system efficiency, but also reduces costly labor-intensive manhours to insulate ductwork in unconditioned space. Based on the required flow rates in cubic feet per minute for each programmatic element served, we used the same ERV system for the units and the common areas. We anticipate that purchasing two of the same piece of equipment would also allow some cost savings in terms of economy of scale. The ERV unit selected is not only HVI certified, but maintains high efficiency levels even when reducing latent moisture in air. General specification information about the ERV unit selected is shown below:


As seen from the sizing requirements, our ERV for the common areas is slightly oversized, but the closest unit to meet our desired cubic feet per minute flow rate. Even more efficiency could be anticipated if there were an ERV unit available on the market that more directly met this specific air flow demand. 5.3.8

Domestic Hot Water

With the large available surface area of the roof on the south faรงade of the building, selecting a solar powered domestic hot water system was a natural choice, in addition to complying with Passive House


standards. The roof of St. Mary’s church is almost a perfect 45 degree angle. The latitude of Pittsburgh is 40.5 degrees, so the roof tilt angle very closely matches the ideal tilt for solar domestic hot water systems, which is essentially equivalent to the latitude [6]. We chose a horizontal array system that could be affixed to the roof with racks that would ensure ideal tilt angle for hot water generation and maximum available roof area for our solar photovoltaic system. We chose a flat plate collector system because of its ability to integrate the best with our storage and backup heat system. Based on our hot water consumption needs, we selected a hot water storage tank that could facilitate an indirect, forced circulation system sized for commercial applications. In addition to being extremely well insulated (double-walled), the storage tank directly connects to the boiler as a hot water backup system, a feature not available on most residential scale hot water storage tanks. Specific information on this system is shown below and included in the specification information.


5.3.9

Electricity

To facilitate our net zero energy objectives, the only suitable renewable energy choice given our constraints was a solar photovoltaic electricity generation system. We chose a highly efficient solar PV system with high wattage output per square foot.

Our sizing strategy including potential output is shown below:


Given this information, we used PV Watts 2.0 to determine our potential electricity generation for the rooftop array. A summary sheet including expected energy savings is shown below.

As a result, we anticipate that the high efficiency solar photovoltaic system chosen will produce 19,389 kilowatt hours per year in Pittsburgh if it is racked to an optimal tilt of 55.5 degrees. We chose a DC to AC


inverter of 90% efficiency. We highly recommend inclusion of a solar photovoltaic array in this scheme given the availability of federal, state, and local incentives that result in a negative payback period and considerable costs savings. A valuable source for estimating cost savings, payback period, and return on investment can be found on www.findsolar.com. We chose not to use this source to size our PV system and estimate electricity generation output because of discrepancies with our PV watts results, which seemed a more reliable software platform. 5.3.10 Appliances & Lighting In an effort to reduce our plugloads, appliance loads, and to comply with IECC 2012 guidelines, we chose a lighting system of 100% compact fluorescent lighting. Although default values are used for HERS index rating in terms of appliance loads, we selected Energy Star rated appliances that not only reduce energy consumption, but also water consumption for selected appliances. Some appliance such as range ovens and clothes dryers are not rated under Energy Star. However, an effort was made to select the most efficient appliances available on the market. Summaries on the selected appliances are shown below and a comprehensive account for their loads are included in our energy balance spreadsheet for this proposal at the end of the report.

5.4 Egg Breaking 5.4.1

Diffused Lighting LED


For our “breaking an egg” requirement, however, we suggest an alternative lighting system that cannot be modeled by the current software, but may prove more appropriate for the demographics of the residents. We recommend providing diffuse LED lighting as it is easier on elderly individuals’ eyes.

5.4.2

Vertical Spandrel Building Integrated Photovoltaic System

To “break an egg” we suggest employing a building integrated photovoltaic panel system attached to a metal support that extends out from the spandrel glass panel. This ensures adequate ventilation behind the pv panel to insure maximum efficiency by controlling overheating and allows a higher performing envelope material to be used in the spandrel panel infill to maximize the R-value. With a tilt angle of 90 degrees, we anticipate the following performance for 96 sq. ft. of this material.

5.5 Compliance 5.5.1

IECC 2012 Guidelines


5.5.2

HERS Rating

5.5.3

URA Guidelines Checklist

Guidelines for building energy efficient homes with the Urban Redevelopment Authority of Pittsburgh (URA) Compliance to Energy Star for New Homes Program – Version 3 Refer to Energy Star Checklist

Compliance to Indoor airPLUS / Water Management Builder and Rater Checklists from ENERGY STAR

☒

Moisture Control Proper drainage of bulk water away from home Proper layering of drainage plane Proper flashing around windows, doors, gutter, roof intersections Radon Control Perforated under slab piping Continuous and sealed under slab vapor barrier (6-mil polyethylene) Internal pipe venting through roof of unit Installation of junction box adjacent to attic piping Access to attic through attic hatch


HVAC Manual J load calculations Use ‘Tight’ under construction quality in Infiltration Section using Simplified Calculation Method Ductwork Sized according to ACCA Manual D, ASHRAE Handbooks All supply, return paths fully ducted All seams and joints sealed with UL-181 No ductwork and mechanical equipment in garage spaces Continuous Ventilation ENERGY STAR rated bath fan with a motion sensor, variable speed control for continuous operation in one upstairs bathroom - Final ventilation rate set after performance testing of air tightness of the building envelope - Following fans qualify – Panasonic WhisperGreen Ventilation Fans Local Exhaust Ventilation Kitchenhoods, bath fans, clothes dryers ducted to outdoors Shortest length of ductwork used All ductwork minimum 4” in dia All local ductwork in rigid sheet metal Seams sealed with UL-181 Ductwork insulation covered with a vapor barrier to prevent condensation Low Emitting Materials Low-emitting materials – ‘off-gas’ harmful chemical like VOC’s and formaldehyde - Certified low-formaldehyde pressed wood materials used (i.e., plywood, OSB, MDF, cabinetry) - Certified low-VOC or no-VOC interior paints & finishes used - Carpet, adhesives, & cushion qualify for CRI Green Label Plus or Green Label testing program

5.5.4

Energy Star Guidelines

Energy Star Qualified Homes National Attached Homes for BOP Requirements Pittsburgh – Climate Zone 5 (prescriptive path requirements) Energy Star HERS Index target = HERS Index of Energy Star Reference Design x SAF -

For apartments in multi-family buildings

SAF = 1 (as specified) Energy Star HERS Index target = HERS Index of Energy Star Reference Design x SAF -

For whole building (detached homes more than 8 bedrooms)

CFA = (600 x 14) + 400 = 8800 sq.ft

Minimum Building Envelope Requirements – Grade I Installation (IP Units as applicable) ☒

Wood Frame Floor over unconditioned spaces Assembly U-Factor = 0.033 Above Grade Walls


Solar Absorptance = 0.75 Emittance = 0.90 Assembly U-Factor = 0.057 Opaque Doors Assembly U-Factor = 0.21 SHGC = N/A Glazing Total Area = 15% of conditioned floor area9 Orientation = Equal distribution on all facades Internal Shade Co-efficient = RESNET Standard External Shading = None Assembly U-Factor = 0.30 SHGC = 0.40 Wood Frame Ceilings Assembly U-Factor

Minimum Heating System Requirements ☒ ☒

90 AFUE Gas Furnace 85 AFUE Oil Furnace 85 AFUE Gas/Oil Boiler 9.25 HSPF/ 14.5 SEER/ 12 EER Air-Source Heat Pump Electric Air-Source Heat Pump Back-up

Minimum Cooling System Requirements ☒

13 SEER AC 14.5 SEER Air-Source Heat Pump

Minimum Service Water Heating System Requirements

☒ ☒

Gallons per day Tank Temperature Gas Storage Tank Capacity 0.63 EF 30 Gallon Tank 0.61 EF 40 Gallon Tank 0.59 EF 50 Gallon Tank 0.57 EF 60 Gallon Tank 0.55 EF 70 Gallon Tank 0.53 EF 80 Gallon Tank Electric Storage Tank Capacity 0.94 EF 30 Gallon Tank 0.93 EF 40 Gallon Tank 0.92 EF 50 Gallon Tank 0.91 EF 60 Gallon Tank 0.90 EF 70 Gallon Tank 0.89 EF 80 Gallon Tank For additional tank sizes Gas DHW EF ≥ 0.69 – (0.002 x tank gallon capacity) Electric DHW EF ≥ 0.97 – (0.001 x tank gallon capacity) Oil DHW EF ≥ 0.61 – (0.002 x tank gallon capacity)

Minimum Thermal Distribution System Requirements ☒ 9

Duct leakage to outdoors ≤ 4 CFM25 per 100 sq.ft of conditioned floor area

If window-wall ratio (WFA) > 15%, Improved U-Value = (0.15/WFA) x Energy Star U-Value


Total duct leakage ≤ 6 CFM25 per 100 sq.ft of conditioned floor area R-8 duct insulation in unconditioned attic R-6 duct insulation in all other unconditioned spaces Supply and return duct locations for basement type foundation in two story building - 50% Attic

-

50% Basement

Thermostat Requirements ☒ ☒

Programmable Thermostat Temperature Set-Points

Infiltration and Mechanical Ventilation System Requirements ☒ ☒

4 ACH50 Infiltration Rate Mechanical ventilation system without heat recovery - Rate: CFM=0.01 x CFA10 +7.5 x (NBr11 + 1) -

24 hours running

-

Fan Watts: Watts = CFM Rate/2.2 CFM per Watt

Exhaust Ventilation

Lighting, Appliances and Internal Gains Requirements ☒ ☒

80% Fluorescent Lighting 423 kWh per year Refrigerator 0.66 EF Dishwasher 122 CFM/Watt Ceiling Fan Energy Star qualified refrigerators, dishwashers, ceiling fans, exhaust fans, CFLs, LEDs, pin-lighting Internal gains

Internal Mass ☒

Internal mass

5.5.5

Passive House Guidelines Checklist

~ 20-30 on the HERS Index EnerPHIT Requirements for Compliance ☒

☒ 10 11

Air Infiltration ≤ 1 ACH @ 50 Pa – Limit Value ≤ 0.6 ACH @ 50 Pa - Target Value Specific Heat Demand ≤ 25 kWh/sq.m.yr ≤ 8 KBTU/sq.ft.yr Primary Energy Usage

CFA – Conditioned Floor Area NBr – Number of Bedrooms

Proposed Retrofit

Notes

≤ 1 ACH @ 50 Pa

Assumption

5.17 KBTU/sq.ft.yr


≤ 120 kWh/sq.m.yr ≤ 38.1 KBTU/sq.ft.yr

27 KBTU/sq.ft.yr

Without renewable energy deductions

Passivhaus Recommendations for Compliance ☒ ☒ n/a n/a ☒

Assembly R-Values (Thumb rule- not specified by Passive House) R-60 Roof (atleast R-38) R- 40 Wall (atleast R-38) R- 30 Basement Wall (atleast R-38) – If conditioned R- 30 Slab (atleast R-38) – If conditioned R-7 Envelope transparent elements (doors, windows)

5.6 Netting to Zero 5.6.1

Site / Source Energy Spreadsheet

In calculating our site and source energy for our proposed model, we made assumptions to try to net zero that the REM Rate software would not allow us to model accurately to achieve a HERS index rating. One change in the Site/Source Energy spreadsheet made was to alter the lighting loads to a more realistic number. LEED for Homes recommends a wattage level of 0.9 watts per square feet of floor area. For our model, this resulted in a lighting load of about 9,000 watts [1]. We anticipated that the lights would be on about 8 hours a day for 365 days a year. This result was inputted into our spreadsheet. In addition, we calculated our plug loads based on the wattage for the appliances that we calculated in part to size our solar photovoltaic system. Wattages were derived from specification sheets for each piece of equipment. These steps significantly helped reduced our plug and lighting loads. We believe these values were more realistic than the numbers derived from the REM Rate model. Additionally, we included the electricity generation from our solar building integrated photovoltaic panels on the spandrel sections of the windows on the south façade. In our REM Rate model, we were only able to calculate the energy generation from our main solar photovoltaic array on the south roof plane.


As a result of these changes, our project came very close to netting to zero with a total net balance site energy consumption of 4,895 kilowatt hours per year. We did, however achieve a very low Energy Use Intensity of 1.65. The benchmark single family residence usually has a site EUI of about 44. This result is particularly exceptional because it is a multifamily project and a retrofit of an existing building. Because the majority of the consumption values were derived directly from our REM Rate model, we were unable to distinguish consumption based on fuel source from the model. As a result our back-up natural gas burning boiler and our oven range are included in the electrical consumption despite consuming natural gas. This does not have a significant impact on our site energy consumption, however, with the high multiplier associated with electricity generation for calculation of our source energy our building may in fact perform marginally better in source energy consumption. Although our proposed building design did not net to zero energy, we believe we made excellent strides with a tighter building envelope and more efficient mechanical system. Our limitations in achieving net zero included limited available roof area to place and size our photovoltaic array and solar hot water array that generated 100% of the daily demand of solar hot water. We believe, however, that this was a reasonable tradeoff.


6 References [1] Lechner, Norbert. Heating, Cooling, Lighting: Sustainable Design Methods for Architects. 3rd Edition. John Wiley & Sons. Hoboken, NJ: 2009. pp. 437 [2] Lechner, Norbert. Heating, Cooling, Lighting: Sustainable Design Methods for Architects. 3rd Edition. John Wiley & Sons. Hoboken, NJ: 2009. pp. 537-538 [3] Lechner, Norbert. Heating, Cooling, Lighting: Sustainable Design Methods for Architects. 3rd Edition. John Wiley & Sons. Hoboken, NJ: 2009. pp. 45 [4] Fuller, Michele. “Lincoln First Friday Artwalk Participating Venues. Available at: http://omahanightlife.com/articles/11052009_omahanightworkspacegallery [5] Image Source: WRK, LLC, 2010 [6] Lechner, Norbert. Heating, Cooling, Lighting: Sustainable Design Methods for Architects. 3rd Edition. John Wiley & Sons. Hoboken, NJ: 2009. pp. 177-206 [7] Air Source Heat Pumps. Heat Pump Reviews website. Available at heatpump-reviews.com [8] Feist, D. (2011 йил September). EnerPHit -Criteria for Residentia-Use Refurbished Buildings. Retrieved 2011 йил November from www.passiv.de [9] Popa, E. A. (2010). The Energetic retrofit of Historic Masonry Buildings - Focus on Central and Northern Europe. [10] Straube, J., & Smegal, J. (2009). Building America Special Research Project: High R-walls Case Study Analysis. [11] Zetalux website. available at www.zetalux.com [12] Wilson, A. (2010 йил 1-June). Avoiding the Global Warming Impact of Insulation. Retrieved 2011 йил 30November from www.greenbuildingadvisor.com: http://www.greenbuildingadvisor.com/blogs/dept/energysolutions/avoiding-global-warming-impact-insulation


Retrofit for St.Mary's Apartments  

Proposed building envelope for St.Mary Church as per Passiv Haus guidelines to reduce heating and cooling loads to design efficient mechanic...

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