Green building (also known as green construction or sustainable building) refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building's life-cycle: from siting to design, construction, operation, maintenance, renovation, and demolition. This practice expands and complements the classical building design concerns of economy, utility, durability, and comfort. Although new technologies are constantly being developed to complement current practices in creating greener structures, the common objective is that green buildings are designed to reduce the overall impact of the built environment on human health and the natural environment by:
Efficiently using energy, water, and other resources Protecting occupant health and improving employee productivity Reducing waste, pollution and environmental degradation
Buildings are the structure of the modern world. They represent society's ingenuity and ability to manipulate our environment into forms that serve our purpose. In many ways, building form and functionality is a reflection of our greater human culture. William McDonough describes a modern advanced building: “ Today even the most advanced building or factory in the world is still a kind of steamship, polluting, contaminating, and depleting the surrounding environment, and relying on scarce amounts of natural light and fresh air. People are essentially working in the dark, and they are often breathing unhealthful air. Imagine, instead, a building as a kind of tree. It would purify air, accrue solar income, produce more energy than it consumes, create shade and habitat, enrich soil, and change with the seasons. ”
CREATED BY : MEET SHAH
If we are to transform our society toward a sustainable future, it requires demolishing the current unsustainable façade of contemporary economic growth and ultimately addressing the inefficiency and waste that supports it.
Why Build Green? Building green saves money The cost per square foot for buildings seeking LEED certification falls into the existing range of costs for buildings not seeking LEED certification. An upfront investment of 2% in green building design, on average, results in life cycle savings of 20% of the total construction costs – more than ten times the initial investment. Building sale prices for energy efficient buildings are as much as 10% higher per square foot than conventional buildings. Real estate and construction professionals overestimate the costs of green building by 300%.
Perceived cost benefits of green building according to building owners:
o Operating costs decrease 13.6% for new construction and 8.5% for existing building projects o Building value increases 10.9% new construction and 6.8% existing building projects o Return on investment improves 9.9% new construction and 19.2% existing building projects o Occupancy increases 6.4% new construction and 2.5% existing building projects o Rent increases 6.1% new construction and 1% existing building projects Why Build Green? Green buildings consume less energy and fewer resources o o o o
In comparison to the average commercial building: Green buildings consume 26% less energy Green buildings have 13% lower maintenance costs Green buildings have 27% higher occupant satisfaction Green buildings have 33% less greenhouse gas emissions
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Why Build Green? Green building occupants are more productive An experiment identifies a link between improved lighting design and a 27% reduction in the incidence of headaches, which accounts for 0.7% of overall employee health insurance cost at approximately $35 per employee annually. Sales in stores with skylights were up to 40% higher compared to similar stores without skylights. Students with the most daylighting in their classrooms progressed 20% faster on math tests and 26% faster on reading tests in one year than those with less daylighting. Corporate perception of whether green fosters innovation: 57% agree; 28% neutral and 15% disagree. Improvements in indoor environments are estimated to save $17-48 billion in total health gains and $20-160 billion in worker performance. Why Build Green? Green building occupants are healthier People in the U.S. spend about 90% of their time indoors. EPA studies indicate indoor levels of pollutants may be up to ten times higher than outdoor levels. Significant associations exist between low ventilation levels and higher carbon dioxide concentrations – a common symptom in facilities with sick building syndrome.
CREATED BY : MEET SHAH
INTRODUCTION : GREEN BUILDING Green building design is a practical and climate conscious approach to building design. Various factors, like geographical location, prevailing climatic conditions, use of locally available and low embodied energy materials and design parameters relevant to the type of usage of the building are normally taken into consideration. Such an approach ensures minimum harm to the environment, while constructing and using the building. A look at traditional building techniques clearly shows that the concept of green or sustainable buildings has existed in our country for a long time. These buildings were generally made of locally available materials like wood, mud and stone and dealt with the vagaries of weather without using a large amount of external energy to keep the inhabitants comfortable. Buildings are among the greatest consumers of energy. Combining cutting edge energy efficient technologies with adaptation of practices used in vernacular architecture which used more of locally available materials and resources is necessary, especially for countries like India where per capita energy consumption is rising rapidly due to high economic growth. This will reduce our dependence on the fossil fuels which have to be imported and are depleting at an alarming rate. A green building uses minimum amount of energy, consumes less water, conserves natural resources, generates less waste and creates space for healthy and comfortable living. When a number of green buildings are located in proximity, they would create a green zone, providing much healthier environment and minimize heat-island effect. The ultimate aim will then be to create many such areas, which would help the towns and cities and therefore the nation in reducing total energy requirement and also the overall global carbon footprint.
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PARAMETERS OF GREEN BUILDING DESIGN : The measures that need to be taken to make a green building can be distributed over three different phases of construction. These are:
Measures taken before construction o Site selection o Soil and landscape conservation o Health and well being o Conservation and efficient utilization of energy and resources o Waste management. Measures taken during construction o Soil and landscape conservation o Conservation and efficient utilization of energy and resources o Waste management o Health and well-being Measures taken to maintain the building during operation. However, there are some genuine overlaps between steps taken before and during construction.
RATING SYSTEMS There are three primary Rating systems in India
GRIHA IGBC BEE
GRIHA stands for "Green Rating for Integrated Habitat Assessment" and has been developed keeping in mind the various conditions and requirements specific to the design and construction of green buildings in India.
IGBC stands for "Indian Green Building Council" and provides the LEED (Leadership in Energy and Environmental Design) ratings for green buildings devised in the United States in India.
The Bureau of Energy Efficieny (BEE) launched a Star Rating Programme in 2009, for office buildings in order to accelerate the Energy Efficiency CREATED BY : MEET SHAH
activities in commercial buildings. The programme developed by the Bureau of Energy Efficiency, BEE is based on actual performance of the building, in terms of specific energy usage (in kWh/sq m/year).
ADVANTAGES OF GREEN BUILDING
Efficient technologies: Green buildings incorporate energy and water efficient technologies that are not as readily available in traditional buildings. These technologies create a healthier and more comfortable environment as they utilize renewable energy, reduce waste, and decrease heating and cooling expenses. Easier maintenance: Green buildings typically involve less maintenance. For example, green buildings generally do not require exterior painting every three to five years: this simple method helps saves the environment, as well as a consumer time and money. Improved indoor air quality: With green buildings, the indoor air quality is improved via natural and healthy materials: green buildings utilize clean energy sources such as solar and wind power, rather than burning coal. Return on investment: Considering the average lifecycle of a building (50-100 years), certain green building measures, such as installing solar panels or doubling the amount of installation, can yield a strong return on investment and lead to higher resale values. Energy efficiency: Green building methods make the most out of energy, resources, and materials. As enforced by The Department of Energy (DOE), builders and design professionals must adhere to energy code requirements. For more information, visit Building to Energy Code. Tax incentives: Incentives exist on a local, state, and federal level to support building green initiatives.
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DISADVANTAGES OF GREEN BUILDING
Cost: Many believe the costs associated with green building make the building methods cost-prohibitive. Air Cooling Features: When utilizing green building cooling components, such as natural ventilation, consumers do not have a precise mechanism to increase or decrease exact temperatures: This is a difficult hurdle for many green building occupants to overcome. Structural Orientation: In order to best optimize sun exposure, green building may demand structural positioning opposite of other neighborhood homes, causing friction among neighbors. In addition, differences in structural orientation will affect how natural daylight enters the building structure: with this in mind there may be a need to install more overhangs, blinds, or shades. Green roofs: In general, green roofs are comprised of multiple layers including a vegetation layer, growing medium, drainage or water storage, insulation, a waterproofing membrane, and roof support. Since they are usually heavier than a traditional roof, builders need to improve upon the existing roof‘s strength in order to install a green roof. Labor Laws: Labor law compliance requirements, in regards to green building, have not fully solidified. For this reason, it is advisable to seek experienced legal counsel in order to avoid costly liabilities.
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THE PROBLEM OF GREEN BUILDINGS: AVOIDING MOISTURE & MOLD PROBLEMS
CREATED BY : MEET SHAH
It’s our belief that the moisture integrity of a building is one of the best report cards on the performance of its design and construction process and the correct use of materials.
After reviewing the designs of lots of new buildings and observing the failures in an equal number of structures we have found the following consistent truths: ■ Building Commissioning— The current industry approach to building commissioning (even the LEED Enhanced Commissioning version EA Credit 3) is unlikely to prevent moisture and similar building failures in almost any climate, except for the most forgiving climate. ■ New Materials— The use of many new building products often have the unintended consequence of performing in unexpected ways, sometimes encouraging significant moisture accumulation and mold growth. Since wall and roof assemblies have historically been high risk areas, it should be no surprise that the increased use of new products in these areas can dramatically increase the overall potential of moisture problems within the envelope. ■ Increased Building Ventilation — The positive benefits of increased outside air ventilation for the occupant‘s health and comfort can oftentimes be outweighed by the increased potential for moisture problems, some of which have caused catastrophic failures in the past. Forensic engineers have strong evidence that buildings can perform in unexpected and damaging ways when additional air is moved through them.
EXAMPLES OF TECHNICAL RISKS FOR CONTRACTORS & DESIGNERS Moisture intrusion, whether bulk water intrusion through the building envelope or a relative humidity increase due to the heating, ventilating, and air-conditioning (HVAC) system, results in a large percentage of construction claims in the United States. Sustainable building practices, some of which are part of the LEED accreditation process, can increase the potential for moisture intrusion if not carefully considered and implemented. Examples include: • Vegetative roofs, which are more risky than conventional roofs (due to the constantly wet conditions) and must be carefully designed, constructed, and monitored after construction. • Improved energy performance through increased insulation and the use of new materials, which may change the dew point location in walls, resulting in damaging condensation and a reduced drying potential for wall assemblies. Lower risk buildings emphasize the drying CREATED BY : MEET SHAH
potential of the envelope over increased insulation. • Reuse of existing buildings or recycled components, which may not be easily integrated to the adjacent new materials and could cause compatibility problems between these materials. • Use of new green construction materials that have not been field-tested over time. The designer needs to assess new materials and their risks compared to traditional materials found in lower risk buildings. • Increased ventilation to meet indoor air quality (IAQ) goals that may unintentionally result in increased interior humidity levels in hot, humid climates. • Building startup procedures, such as ―building flush-out,‖ which could result in increased humidity levels and mold growth. Lower risk buildings rely almost exclusively on source control (which is also a green building goal) rather than relying on ―flush-out‖ and increased building exhaust. Through our evaluation of various LEED credit opportunities for designers, we hope to establish the fact that a sustainable building must be equally designed to prevent likely moisture and mold problems. We believe that a building attaining LEED certification is not necessarily a building with a low potential for failure due to moisture intrusion. However, it is our belief that it is possible to combine LEED certification with the best practices for moisture and mold problem avoidance – but it will require extra effort from both architects and mechanical engineers. An important aspect to avoiding moisture problems in green buildings is the inclusion of the best practices from the waterproofing/ HVAC (heating, ventilating, and airconditioning) disciplines in combination with the LEED certification principles. It is unwise to assume that LEED certification has automatically incorporated those best practices. Green building practices must always be subservient to best design practices in areas such as exterior waterproofing, good humidity control, and proper due diligence in selecting new construction materials. In order to facilitate the dual vision of an environmentally sensitive building with a highly durable, well performing, moisture resistant building, we have compressed a significant amount of data into the following discussion. This discussion moves from an overview of LEED® certification points with potential moisture issues (shown in a table) to a more detailed analysis of several specific LEED credits that we view as examples of high risk. These are credits that align with the consistent truths we listed above concerning building commissioning, new materials, and ventilation issues. The concerns raised in the following pages are not climatically or regionally specific, but are universal concerns for all but the most forgiving climates. Forgiving climates would include those areas with very low rainfall, year-round moderate temperatures, and minimal humidity levels. Even in those climates specific building types could be expected to exhibit problems if best practices are not followed.
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OVERVIEW OF LEED CREDITS THAT HAVE INCREASED POTENTIAL FOR MOISTURE & MOLD PROBLEMS : The following is a summary of LEED Credits that, if not carefully considered, designed, and constructed, have the potential for creating moisture and mold problems. This summary also includes LEED Credits that can be enhanced to minimize the potential for moisture and mold problems:
LEED CREDIT NUMBER
Sustainable Sites (SS) Credit 7.2
Heat Island Effect: Roof
Option of installing a vegetated roof for at least 50 percent of roof area.
Vegetated roofs have more moisture due to irrigation and constant hydrostatic head of water than typical roofs, making it difficult to prevent water intrusion and condensation problems. Moisture migration & concentration between impermeable membranes is a possibility.
Energy & Atmosphere (EA) Prerequisite 1 and EA Credit 3
Fundamental Commissioning of the Building Energy Systems and Enhanced Commissioning
Enhanced commissioning addresses only the most forgiving climates.
1. The typical commissioning design review is not likely to predict the potential for future moisture and mold problems.
Minimum Energy Performance Required and Optimize Energy Performance
Increases in energy performance can reduce moisture control in buildings.
EA Prerequisite 2 and EA Credit 1
2. The reviews normally do not incorporate an analysis of the building envelope performance. 1. Increased thermal insulation changes wall system performance (dew point location) with possible condensation in wrong location. 2. Modifying heating, ventilating, and air-conditioning (HVAC) control schemes alters equipment run times and impacts moisture control.
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EA Credit 5: Measurement & Verification
Ongoing energy measurement and verification
Sacrificing adequate relative humidity control to reduce energy usage.
Any good energy management plan must be subservient to adequate moisture control.
Materials and Resources (MR) Credits 1.1 and 1.2
Building Reuse: Maintain 75 percent to 95 percent of Existing Walls, Floors, & Roof
Moisture control performance of existing building envelope components re-used under this credit.
1. Quality and performance of existing components such as flashing, rainwater barriers, air barriers, need to be investigated and possibly tested. 2. Model both new and re-used component to identify how each component will act towards good moisture control â€” this includes interaction with the HVAC system.
MR Credits 1.3, 2.1, 2.2, 3.1, and 3.2
Building/Materials Reuse and Construction Waste Management
Inadvertent reuse of previously water damaged and/or mold contaminated materials presents an increased risk. Construction workers at risk of handing mold contaminated materials.
1. Mold contamination is not often visible in the occupied side of materials and is not generally found by air testing in a construction environment. Destructive testing and evaluation may be required. 2. Construction waste management plan may need to include section on handling moldy materials.
MR Credit 6
Rapidly Renewable Materials
Use of rapidly renewable natural building materials and products without understanding their properties related to water (permeance, absorption, etc.).
The mixture of synthetic materials with natural materials in the building envelope can create increased potential for moisture condensation and entrapment.
Indoor Environmental Quality (EQ) Prerequisite 1, EQ Credit 1, and EQ Credit 2
Minimum Indoor Air Quality (IAQ) Performance, Outdoor Air Delivery Monitoring, and Increased Ventilation
Ventilation in many parts of the United States must to be carefully designed to avoid moisture problems.
Increased ventilation air should never be added without an overriding control of both pressurization and dehumidification.
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EQ Credit 3.1
Construction IAQ Management Plan: During Construction
Typical construction sequencing does not always allow for meeting credit objectives for protection of materials from water damage.
Construction sequencing needs to be reviewed and material protection measures understood and enforced.
EQ Credit 3.2 (and 3.1)
Construction IAQ Management Plan: Before Occupancy
Pre-occupancy flush out.
Introducing required air for this credit in many geographic areas can result in indoor moisture problems.
EQ Credit 5
Indoor Chemical & Pollutant Source Control
Requires significant exhaust rates for source control.
Local exhaust can result in local depressurization and introduction of humid outside air into building envelope. It can also result in inadvertent pollutant movement within a building.
EQ Credit 6.2
Controllability of Systems: Thermal Comfort
Providing operable windows can allow untreated humid air or rainwater to enter building.
If operable windows are installed, consider sensors and automatic overrides.
Innovation in Design (ID) Credits 1.1-1.4
Innovation in Design
Recognizing the inherent increased risk of using new products that have less in-field experience.
1. Probably unrealistic for the design and construction team to understand the performance characteristics and limitation of new products and the additional risks that their use might carry. 2. Particular concern about the introduction of new products into the highest moisture risk areas of the building (i.e., the envelope and the HVAC system) since in these areas there is added risk.
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FUNDAMENTAL COMMISSIONING (EA PREREQUISITE 1) AND ENHANCED COMMISSIONING (EA CREDIT 3) Intent of EA 1: Verify that the building’s energy related systems are installed and calibrated, and perform according to the owner’s project requirements, basis of design, and construction documents. Intent of EA 3: Begin the commissioning process early during the design process and execute additional activities after systems performance verification is completed. Building commissioning (even the enhanced version of commissioning in LEED EA Credit 3) is not likely to prevent catastrophic moisture and mold problems. Traditional commissioning fails to accomplish two primary requirements in avoiding moisture problems: 1. The design review is not likely to be a ―standard of care‖ technical peer review, but is more often a review intended to determine if the constructed building, once built, can be commissioned and if the design meets the Owner‘s intent. In our experience the typical design review will not predict the potential for moisture and mold problems. Without this prediction it cannot offer specific solutions to avoid them. 2. These reviews are not required to incorporate an analysis of the building envelope‘s performance—the acknowledged component that fails the most frequently and usually the most dramatically. What the building science industry has known for some time is that moisture and mold problems are often very predictable, even in the early design stage. However, for this analysis to be successful the review team must be very savvy about what combination of design choices create a high risk of causing problems and what other choices are lower risks. Figure 3.1 shows an example of the predictability of moisture and mold problems in a hotel type building. Some concepts that should be included in building commissioning to reduce the possibility of moisture and mold problems include the following: ■ During the design phase a technical peer review of the document should identify issues which will likely be major cause of moisture and mold problems in the operating building. This review may need to be accomplished by someone other than the traditional commissioning agent since they may not have the requisite skill set to conduct this type of analysis. It‘s our opinion that this review needs to specifically identify which building components and systems have a high potential for moisture problems and offer alternative solutions to the design team. CREATED BY : MEET SHAH
FIGURE 3.1: Prediction chart of the probability of moisture and mold in a hotel-type building with a series of HVAC system choices and an unforgiving wall system—i.e., a misplaced vapor retarder in conjunction with moisture sources. Other combinations of decisions can increase or decrease the risk. (Note: This example makes numerous assumptions such as there are no significant rainwater leaks. This prediction chart also assumes that the outside moisture conditions are conducive to mold growth.)
■ The commissioning process needs to consider the interrelationship of the building envelope and the HVAC system. This area is often overlooked because it involves the dynamic interaction between two separate technology areas. ■ The building envelope needs to be commissioned in a manner that would avoid rainwater leaks, excessive air leakage, and condensation problems. In cases where the envelope is commissioned, both individual envelope components (like windows) should be tested as well as assemblies of multiple adjacent components. Testing individual components does not address the connection points and intersections between various envelope components where most of the failures occur. Assembly testing can include a mix of qualitative (Figure 3.2) and quantitative testing, such as ASTM tests.
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FIGURE 3.2 : Qualitative water testing of window and stud wall assembly after installation of membrane water proofing. Note spray rack (red arrows) above and to the side of window that washes the wall while the cavity side of sheathing is checked for leaks.
â– Construction phase commissioning of envelope components may require adjustment
of installation methods based on test results. Checklists should be developed that allow for certification that such adjustments are implemented (Figure 3.3)
. FIGURE 3.3 : Checklists for commissioning of sliding glass doors. These checklists are completed by the contractor. The checklists may be modified after installation and quantitative testing of the first several doors.
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MATERIALS & RESOURCES AND OTHER CREDITS: USE OF NEW MATERIALS IN HIGH RISK LOCATIONS Intent of these 14 Materials & Resources Credits: Reuse of existing building components, the management of construction waste, materials reuse, amount of recycled content, the use of regional materials, the use of rapidly renewable materials, and the use of certified wood.
New green materials can often meet requirements in several LEED credits. For example, organic-based insulation materials can satisfy LEED Material & Resource Credit 6 as a rapidly renewable material, Energy & Atmosphere Prerequisite 2 and Credit 1 for energy performance, and Indoor Environmental Quality Credit 4.1 for low emitting materials. Many new materials and concepts can also fall under the Innovation & Design Process credit requirements for developing new solutions, employing new technologies, or realizing exemplary performance. We believe that it is reasonable to assume that if we are relatively unfamiliar with a new materialâ€˜s individual performance then we probably know even less about the materialâ€˜s interaction with other adjacent components. Our ignorance about the performance of new materials should not be disregarded because the manufacturer of these materials assures us that the product is appropriate for LEED-certified buildings. The recognition of additional risk in the use of innovative products (especially in the envelope and HVAC systems) by the development team should demand a higher degree of rigor in the evaluation of these products. As previously mentioned, the interaction between the HVAC system and the envelope creates an unusually high risk area. The impact of this condition is that any deficiency in either system can cause dramatic building-wide moisture problems. It may be only a slight overstatement to state that there is no wall system which a creative architect can envision that a poor HVAC system cannot destroy. Conversely, a very well performing HVAC system can often compensate for a marginally designed (or constructed) building envelope to the point where many moisture problems may never be noticed. However, there is a point where even an exceptionally well performing HVAC system cannot compensate for a poorly designed wall system, especially a wall that allows rainwater intrusion or is excessively leaky to air movement.
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FIGURE 3.4: Example of the amount of water absorbed by a wall insulation product. This experiment demonstrates that many products intended for wall and roof assemblies can absorb huge amounts of water in spite of their data sheets attesting to the opposite.
A simplification of the above concept can be stated as: ■ Bad Envelope Design + Bad HVAC Design = Guaranteed Moisture Problems ■ Good Envelope Design + Bad HVAC Design = Likely Moisture Problems ■ Bad Envelope Design + Good HVAC Design = Likely Moisture Problems ■ Good Envelope Design + Good HVAC Design = Likely Success ( Note : The term ―Good Envelope Design‖ refers to the correct design and construction of the air barrier, vapor retarder, and thermal barrier. It does not refer to rainwater intrusion issues since even minor rainwater entry past the water resistive barrier can be problematic. ―Good HVAC Design‖ refers to the proper building pressurization for the specific climate, proper dehumidification, and proper air distribution within a building )
Although new wall system products are often intended to provide better thermal insulation, reduce air movement through the walls, or allow enhanced drying of the wall assembly (via vapor diffusion) they can also perform in unanticipated ways. These new products can dramatically change the way moisture flows through wall and roof systems and the potential for condensation within these cavities. The use of these new products mandate that the designer implement several additional steps to avoid problems: 1. Better understand the performance characteristics of these new products. This may require a more rigorous evaluation of these materials than is required with traditional products. As with any product —but more so with new products—the performance answers may not be found in the product data sheets, but may require experiments and mockups to determine their performance. CREATED BY : MEET SHAH
This type of evaluation may be beyond the scope and expertise of the design team — but it should nevertheless be implemented. In Figure 3.4 above, a new insulation material (marketed for ―green‖ buildings) was able to hold a considerable amount of water despite a data sheet that indicated it was a non-absorptive product. The use of this material in wall cavities could create massive mold problems if there is water leakage through the water resistive barrier since the normal wet-dry cycling will not likely occur. 2. Analyze the vapor retarder, air barrier, and bulk water retention properties to better understand where the material should be placed, if at all, within the wall system. 3. Model the wall systems for performance during the early design stages to predict the potential for water vapor transmission through the wall assemblies and potential for condensation to occur. Minimally, this modeling should predict the dew point location and the vapor transmission profile during the most extreme season for the location. 4. Perform a three-dimensional analysis of rainwater barrier geometry, especially at complex joints and changes in plane. All other standard good practices for wall system design should continue to be followed whether new or traditional products are used including: ■ The use of water resistive barriers as the first line of defense, ■ Designing drainage planes to channel water down and out of the envelope, ■ Installing secondary barriers for redundancy ■ Designing proper flashing and sealant joints.
INCREASED VENTILATION (EQ CREDIT 2) Intent: Provide additional outdoor air ventilation to improve air quality for improved occupant comfort, well being and productivity. For decades there have been competing arguments within the mechanical design community on whether to increase or decrease the amount of outside air that is introduced into commercial and institutional buildings. Although there are sound arguments on both sides of the debate, today‘s emphasis on increased building ventilation to achieve LEED credits has given an added incentive to increase the amount of outside air to buildings. The experience of many forensic building experts (especially in the eastern half of the country) do not necessarily support the theory that adding more outside air creates a better performing, more sustainable building—sometimes quite the opposite (Figure 3.5).
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FIGURE 3.5: Martin County Courthouse, Stuart, Florida. The HVAC design produced high rates of outside air ventilation but poor temperature and humidity control which contributed to mold and moisture problems, resulting in over $10 million in renovation costs for a 3-year old building.
What is known about ventilation air is that in regions with ambient high dew point conditions and elevated relative humidity levels (which include much of the entire eastern half of the country during portions of the year) there is a direct correlation between the number of moisture problems and increased rates of mechanical building ventilation. This can occur for obvious reasons, such as the additional moisture load that is introduced into the building along with the outside air. However, more obscure reasons can also increase the risk of adding outside air to a building. Unbalanced (or partially depressurized) buildings can be the result of moving large amounts of air around a building. When this condition occurs moisture problems become more prevalent. These unbalanced conditions happen when air is trying to flow from the supply side of the air handler equipment to the return side but is restricted by structural or architectural barriers. Florida Solar Energy Center (FSEC) of Cocoa, Florida called this condition the â€•Smart Air Syndromeâ€– conceptâ€”that air is supposed to be smart enough to get from one place to another in spite of barriers. Additional ventilation air should always be designed in conjunction with considering the impact of the distribution of the ventilation air. This requires identifying parts of the building that could become depressurized with respect to outside conditions, thus potentially drawing humid outside air into the envelope cavity or occupied spaces. (Note: Even in less humid climates an unbalanced HVAC system can inadvertently transfer odors and airborne pollutants in unintended ways through a building.) This increased risk of moisture problems caused by greater air volumes (and thus unbalanced areas of the building) is depicted in the FSEC graphic below (Figure 3.6).
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FIGURE 3.6: FSEC graphic on risk of Building failures related to Building complexity and Intensity of HVAC drivers (air volumesand pressures). Source: 1996 Florida Solar Energy Center (FSEC) Study.
FSEC‘s research has demonstrated the relationship between building complexity (architectural and structural complexity), the intensity of the HVAC drivers (air volumes and pressures), and the risk of building failures. The solution is not to build simpler, less ventilated buildings but it is to insure that the ventilation air is effectively delivered to the space. This means that ventilation must be distributed so that it not only reaches the desired breathing zone but does so in a manner that does not adversely affect the building. The HVAC system that introduces ventilation air must also do so in a manner that properly dehumidifies the air. The ―golden rule‖ of moisture control is that under no circumstances should adequate dehumidification be sacrificed for increased ventilation. In many regions of the country during summertime conditions the moisture load contributed by the outside air can exceed the amount of moisture that the air conditioning system can effectively remove. The solution is to address these risk factors in several ways: ■ Insure the correct distribution of air flows within buildings (to avoid pressure imbalances). This can usually be accurately predicted during design. ■ Increase the verification of HVAC system performance by adding additional elements to the building startup and commissioning programs. This post-construction verification includes detailed pressure mapping of the building to confirm proper air distribution and using temperature and relative humidity (RH) data-loggers to confirm conditions during the first year‘s operation. This pressure mapping and data logging needs to also include the building cavities—areas that are often ignored. Many of these elements are frequently absent in today‘s standard HVAC system startup and building commissioning programs. What experience demonstrates is that increased amounts of outside air can be safely added to a building if the known causes of increased risk (such as proper air distribution) are addressed during design and verified after construction. CREATED BY : MEET SHAH
CONSTRUCTION IAQ MANAGEMENT PLAN DURING CONSTRUCTION AND BEFORE OCCUPANCY (EQ CREDITS 3.1 AND 3.2) Intent: Reduce indoor air quality (IAQ) problems resulting from the construction/renovation process in order to help sustain the comfort and well-being of construction workers and building occupants.
During construction there can be increased pollutant load in a building because of various factors: heavy particulate load and the off gassing of formaldehyde and volatile organic compounds (VOC‘s) from newly installed products. There are various methods of controlling this additional pollutant load such as additional air filtration, the use of temporary air handlers for heating and cooling, and flushing out the building with additional amounts of outside air. As proposed by LEED Credit 3.2 building flush out can occur either late in the construction phase or after the building is occupied. While the use of outside air to flush out the building may reduce the concentration of off gassing it can also inadvertently cause moisture problems. Although the moisture problems may be short term (decreasing after the flush out is finished) the resultant mold problems could be long lasting. The EQ Credits related to the Construction IAQ Management Plan allow for two separate approaches to building flush out, one during construction and an alternative plan after occupancy. Both approaches involve a substantial amount of outside air volume— 14,000 cubic feet (cfm) per square foot (SF) of floor area. Whether this flush out occurs rapidly over a several week period (during the late stages of construction) or more slowly over several months (during post construction) moisture problems are likely to result in many parts of the country during the summertime. Increased building ventilation over the design amounts can create a range of problems such as inadequate sizing of the air filters and an inability of the air conditioning equipment to handle the increased moisture (or latent) load. While the LEED credit mandates a 60 percent RH maximum level during this flush out period this requirement may not be feasible with the building‘s equipment. Since final building finishes should be in place prior to flush out (otherwise there are no materials to off gas) it makes the entire building susceptible to mold growth problems. If building flush out occurs after occupancy then even the furnishings are susceptible to moisture problems. In a typical 100,000 square foot building the amount of outdoor air required to meet the flush out portion of this credit is 1,400,000,000 cubic feet. This amount of air volume in the eastern portion of the country during the humid summer months can be equivalent to over 200,000 gallons of additional moisture introduced into the building. This moisture is in CREATED BY : MEET SHAH
addition to the normal moisture load from construction activities, cleaning liquids, or construction-related moisture from curing concrete, paint drying, etc. One of the additional risks with conducting building flush out (especially in an occupied building) is that it is usually done in the evening when the heat load (sensible) is the lowest and the moisture load (latent) is the highest. This can result in even greater relative humidity levels in the building because the unfavorable ratio of sensible to latent load can either cause overcooling of the building (resulting in flash condensation). The additional likelihood that the HVAC system might still be unbalanced at the time of the flush out increases the potential for moisture problems as the result of this process.
INDOOR CHEMICAL & POLLUTANT SOURCE CONTROL (EQ CREDIT 5) Intent: Minimize exposure of the building occupants to potentially hazardous particulates and chemical pollutants. Depending on the climate where the building is located it may be important to utilize different types of ventilation approaches to control indoor air quality degradation and indoor chemical and pollutant source control. In climates with outdoor air conditions that carry large summer moisture loads (which includes much of the eastern portion of the country), ventilation approaches should include a combination of exhaust and make up air to achieve the pressure differentials required by the credit. This credit requires a pressure differential of 5 Pascal‘s (Pa) between the area with the chemical or pollutant source and adjacent areas. The recommended approach is to exhaust the space with the chemical or pollutant source to a point that is at least 5 Pa negative when compared to adjacent areas and a minimum of .50 cfm per SF. If this recommendation is incorrectly applied its result can create depressurization of the entire building (or portions of the building). The inherent risks associated with increased building exhaust as recommended in this LEED credit are numerous: ■ It increases the importance of a very accurate test and balance process to insure that adjacent building areas are not accidentally depressurized (including wall and ceiling cavities). ■ The suggested pressure differentials (5 Pa) are significantly more precise than the average test and balance firm can measure, likely leading to errors. ■ Since the suggested exhaust rates and pressure differentials are minimum figures there might be a tendency for some practitioners to vastly exceed these amounts (under the CREATED BY : MEET SHAH
concept that ―more is better‖) which could result in an even increased potential for uncontrolled air flows and moisture problems. It has been the experience of many practitioners in the field of forensic building science that achieving negative pressure conditions in parts of a building, while maintaining overall positive building pressures elsewhere is an extremely delicate balance to achieve.
SOLUTIONS The green design movement is transforming the design and construction marketplace like no other innovation in the lifetime of most designers. Green design has brought to the forefront of the design and construction community a holistic view of how to design, build, and operate higher performing buildings. As such, the noble goals espoused by sustainable development and green buildings are certainly worth aggressively pursuing — but it must be done with significant care, especially in the areas of high risk for moisture and mold problems. It seems that some of the ―best practices‖ and ―lessons learned‖ in other fields are not being applied in a precise enough manner when it involves green construction, at least as that applies to moisture control. To summarize our recommendations we believe that the following should occur in an effort to enhance green designs: ■ A technical poor review of the design should be implemented that attempts to predict the building performance with the new materials and products. At a minimum this review would focus on the HVAC and building envelope systems that are most exposed to moisture-related failures. This should provide a more climatologically and regionally accurate green design. ■ The design team must be confident that they have incorporated the institutional knowledge already known in the fields of humidity control, waterproofing and building envelope performance. Processes that have already lost favor in the indoor environment field, such as ―building flush out,‖ should not now be incorporated into green construction as ―best practices.‖ These processes have historically shown little benefit and have demonstrated high cost, high risk, or both. ■ The acceptance of new products with specific ―green‖ benefits should be especially scrutinized. Our experience is that gaining performance in one area often means sacrificing performance in another area. If the area where performance is sacrificed is a critical parameter (such as the water absorption qualities of wall insulation) then the risk may be too great, no matter what the benefit is. We are not sure if it‘s realistic for a design team to make all of these required assessments, but without it building failure seems more probable. CREATED BY : MEET SHAH
PHOTOGRAPHIC CASE STUDIES
CII – SOHRABJI GODREJ GREEN BUSINESS CENTRE HYDERABAD Introduction The CII – Sohrabji Godrej Green Business Centre in Hyderabad is the first LEED Platinum rated building in India. Locally available materials and sustainable energy sources have been used extensively in the building. Natural lighting and ventilation enhance the energy-efficiency of the building. Adequate green spaces help in controlling the micro-climate providing visual delight at the same time.
Aerial view of CII-Godrej GBC, Hyderabad showing wind towers, solar photovoltaic panels and green roofs. CREATED BY : MEET SHAH
Location, Orientation & Climate
It is located in HITEC City, a major technology township in Hyderabad. Use of vehicles that run on alternative sources of energy is encouraged. Use of such vehicles helps in saving energy.
There is a vast difference in the amount of glazed areas on the northern and western sides of the building. Such features prevent unwanted heat gain.
Existing features in the landform have been integrated into the design without causing much harm to the local eco-system.
Rocks existing on site have been retained and integrated in the building design CREATED BY : MEET SHAH
The building is designed to maximise usage of natural light for daylighting without getting unwanted heat inside. The ground surface covered by the building is replaced through roof gardens which play a major role in insulating the building.
Roof gardens insulate the building from solar heat
Unwanted gain of heat is reduced through simple design principles like earth berming. Heat gain through openings is also reduced through intelligent design of windows.
Intelligent design of windows allow in light but keep the heat away CREATED BY : MEET SHAH
An effective combination of closed and open spaces help in modulating the micro-climate so that it keeps the building cool and well-ventilated. There is ease of access throughout the site.
A combination of open and closed spaces keep the building cool and well-ventilated
Materials & Appliances
Use of local materials and materials with lowembodied energy is visible at various places. For instance, local stone and waste construction materials are used for external cladding.
Old furniture has been used in different parts of the building.
Locally available materials like stone and wood are used in the school CREATED BY : MEET SHAH
Old furniture used in the cafeteria negates the energy consumed in making new furniture
Emphasis is laid on providing adequate day-lighting. ď‚ˇ Intelligent design of windows such as different windows for views and for light reduce the heat gain.
Abundant natural light is available in office spaces CREATED BY : MEET SHAH
Effective measures are taken to properly ventilate the building while saving energy at the same time. Air caught by the wind towers is carried through an earth-air tunnel which pre- cools the air entering into the AHU‘s. This saves energy required in the cooling process.
Wind towers carry air through an earth air tunnel to cool it before being supplied to the AHU’s ‗Jaalis‘ on the outer façade of the building also help in cooling, shading and ventilation of the building.
‘Jaalis’ help in cooling and shading the building and inducing ventilation CREATED BY : MEET SHAH
Solar energy is used to generate electricity that is used in the building.
Solar photovoltaic panels on the roof generate electricity for the building
Use of vehicles that run on alternative sources of energy is encouraged.
Use of battery operated vehicles is encouraged
Rain water is recharged into the ground. The landscaped garden has a variety of local plants and trees which require less water for irrigation. The garden has been designed such that all rainwater is retained. CREATED BY : MEET SHAH
Rain-water is harvested in the landscaped garden ď‚ˇ ď‚ˇ
All waste water is treated in a root zone treatment facility. The treated water is used for flushing toilets and irrigating the garden.
Waste water is treated in the root zone treatment facility
CREATED BY : MEET SHAH
DRUK WHITE LOTUS SCHOOL LADAKH Introduction The Druk Padma Karpo School near Leh is a Buddhist school under the patronage of the Dalai Lama, and founded by His Holiness the 12th Gyalwang Drukpa in 1992. Designed by international architects Arup Associates, the school building combines the best of traditional Ladakhi architecture with cutting-edge engineering excellence to act as a model for appropriate, cost effective and sustainable development. The innovative architecture of the school has won several international design awards, including the 2002 World Architecture Awards for Best Education Building, Best Building in Asia, joint winner for Best Green Building, an award for ‗Inspiring Design‘ from the British Council of School Environments and a ‗Design for Asia Grand Award‘.
The secondary school block
Location, Orientation & Climate
The Druk School is located at Shey, about 15 kms to the south-east of
Around 60 % of the students and the teachers come from nearby towns and villages using public transport or school buses while the remaining students are accommodated in the residential facilities. Overall, there is minimal usage of personal vehicles by the teachers or students while commuting to the school. All these combined result in a lot of energy savings. The classrooms are oriented 30 degrees east of south to utilise the morning sun for natural lighting and space-heating. CREATED BY : MEET SHAH
Natural lighting and heating of classrooms are optimised by their orientation
The residential blocks are oriented in the east-west axis with the living quarters facing south to facilitate solar heat gain. Circulation areas are placed on the colder north side. The natural slope of the site provides for universal access.
South facing residential blocks utilise the sun’s heat to generate warmth inside while the natural slope provides universal access
The natural soil condition aids water from melting snow or rain to seep into the ground thus recharging the ground water. The negligible amount of hard paving in the site ensures that almost all snow or rain falling on it is recharged into the ground. CREATED BY : MEET SHAH
Open grounds of the school aid ground water recharge
Willow trees found on the site are pruned to maximise heat and light gain in the winters. The waste wood is then used as fuel for the ‗bukharas‘ for space heating purposes.
Waste wood from willow trees found in abundance in Leh are used as fuel for the ‘Bukhara’.
Architectural Design The school has been designed such that all natural and renewable sources of energy are utilized to the maximum possible extent without causing any disturbance to the environment. At the same time adequate measures have been taken to insulate the building so as to reduce loss of heat. The 700 mm external walls are made of 150 mm thick mud bricks on the inside and 450 mm thick granite blocks on the outside with a 100 mm air gap in between. These walls insulate the building from the cold and windy conditions outside. CREATED BY : MEET SHAH
Mud-brick walls are clad with granite on the outside ď‚ˇ
The southern side of all the buildings are provided with windows which allow natural light inside. These are opened during the summers for ventilation and are shaded with removable wooden shades.
Glazed southern side of classrooms provide light, ventilation and warmth ď‚ˇ
Roofs are insulated with a 50 mm thick layer of grass topped with a 300 mm thick layer of mud and clay. Skylights are provided in the roof to supplement light coming in from the windows.
CREATED BY : MEET SHAH
Light coming in from the skylights
Materials & Appliances
Almost all the materials used in the complex have been sourced locally. Wood from willow and poplar trees are used for the structure, roofs, floors and windows. Granite blocks and mud-bricks are used for the external walls. All internal walls are also made of mud-bricks. Concrete used is limited to the foundations of the wooden columns, as mortar and for the floor below the ‗Bukhara‘.
Locally available materials like stone and wood are used in the school
CREATED BY : MEET SHAH
Artificial lighting is not required in the classrooms most of the time due to the abundant natural light available. Electricity usage during the day-time is limited mainly to computers and other such peripherals. Energy saving lighting fixtures like CFL lights are used.
CFL Lamps are used wherever artificial lighting may be required
The abundant sunlight available has been used to maximise natural light in the academic section. Light from the windows and skylights eradicate the need for artificial lighting. The windows are shaded in the summers so as to allow light in but keep the heat away. All blocks are well-separated so that there is no mutual shading.
Abundant natural light is available in the classrooms CREATED BY : MEET SHAH
Ventilation High level openings work in conjunction with the south facing windows to provide ventilation required in the building. In the residential areas, the Trombe walls are provided internal dampers and also with such openings in the internal walls and . Together, they ensure an effective ventilation system where wind drafts do not cause inconvenience to the children sleeping inside.
Dampers placed above and below windows are part of the ventilation mechanism in the residential areas
Renewable Energy ď‚ˇ
Solar Energy is used for a number of purposes like day-lighting, direct heat gain through the windows and to induce ventilation through the Trombe walls. ď‚ˇ Solar water heaters are used to heat the water required for washing purposes.
Solar water heaters are placed near wash areas and provide the required hot water CREATED BY : MEET SHAH
Solar electricity is generated and used for a number of purposes. Besides providing electricity for general lighting at night, computers also run on solar electricity. The latter is also used to run the water pump that pumps water from a depth of about 30 metres.
Solar Photovoltaic Panels which generate all the electricity required in the school
All snow and water is recharged into the ground. Dry toilets eradicate the need of water for flushing purposes. Waste water from bathrooms and the dining hall kitchen is used to irrigate the vegetable gardens.
The soft ground surface facilitates all the snow and water to seep into the ground CREATED BY : MEET SHAH
Traditional dry latrines have been improved and problems of fly and odour eliminated in the ‗Ventilation Improved Pit‘ (VIP) toilets. A double chamber system with a Tin sheet facing the south acts as a flue carrying the odours out. A mesh at the top of the flue prevents flies and insects from coming in. The VIP toilets act as composting toilets and produces humus that can be used as fertiliser. Moreover, they do not need water.
The ‘Ventilation Improved Pit’ Toilet which is an improvement of the traditional Ladakhi dry toilets
The use of local materials which are abundantly available ensures minimal damage to the environment during construction. As most of the construction workers were locals, little energy was spent for their accommodation and travel.
CREATED BY : MEET SHAH
Materials used in construction have mostly been sourced locally
Post Construction ď‚ˇ
The school is being built in phases and the entire complex of the school is scheduled to be completed in 2011. ď‚ˇ This has helped in learning from the first phases and using this experience in optimizing the usage of materials in the later phases.
CREATED BY : MEET SHAH
VIDEOGRAPHIC CASE STUDIES
MR. MAHENDRA PATEL’S RESIDENCE AHMEDABAD
Ahmedabad.WMV Mr. Mahendra Patel‘s residence , built in 1997, is a good example of an individual residence which maintains high living standards without depending much on external sources of energy, primarily the city supply grid, Through good design and use of materials, the building responds to the high summer temperatures so as to reduce the load on the cooling systems.
CREATED BY : MEET SHAH
BCIL TZED BANGALORE
BCIL TZed is a LEED Platinum rated group housing society which combines good design and usage of materials and technology to ensure that comfort levels are maintained without using much energy. The moderate climate of Bangalore reduces the energy consumption of buildings for space conditioning.
IRRADâ€™S OFFICE GURGAON
Gurgaon.WMV The Institute of Rural Research and Development (IRRAD)â€˜s office building in Gurgaon is a sustainable building designed to meet the extremes of the composite climate that is prevalent in many parts of the country including Delhi. It is a LEED Platinum rated building. CREATED BY : MEET SHAH