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< Previous8 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION 1 .1 The Evolution of Canadian Housing Technology Over the past 60 years there have been many changes to the way houses are built in Canada ( Table 1.1 ). Adjustments and innovations have resulted in a better housing product, consisting of higher quality materials and systems. Changes have also resulted in increased productivity on the construction site, allowing a quality product to be built in a shorter period of time. Homes today are far superior in terms of energy efficiency, environmental responsibility and occupant satisfaction, with high levels of comfort, convenience and peace-of-mind. Energy efficiency increased in importance for builders and their customers after the oil price shocks of the mid and late 1970s. As energy prices increased, Canadian builders began to look for ways to improve energy efficiency. In Saskatoon, researchers and builders developed “super energy-efficient” homes that could be heated for only a few hundred dollars a year. In 1980, the federal government decided to stimulate the rate of construction of more energy-efficient homes by establishing the Super Energy Efficient Home (SEEH) Program. Under this program, Natural Resources Canada (NRCan) provided builders with training and incentives to construct what are now called R-2000 homes. In 1982, the Canadian Home Builders’ Association (CHBA) assumed responsibility for the delivery of the R-2000 Program. Although delivery shifted to a provincial model in the 1990s, CHBA retains a strong role in supporting R-2000 and beyond. CHBA is working to assist builders in constructing and labeling Net Zero Homes, Renovations, Communities and MURBs. The R-2000 program’s main achievements include providing technical training to builders across the country, and serving as a catalyst for the research and development of technologies that enhance the energy efficiency of all homes built in Canada. Net Zero Housing is possible because of the foundation laid by R-2000. Table 1 .1 The evolution of house construction AreaPracticeAdvancement or trend Basement1940s 1960s 1980s 1980s, 1990s 1980s, 1990s 2000s Concrete block and site-mixed concrete; forming lumber reused as wall and roof sheathing Ready-mixed concrete and prefabricated formwork Some use of preserved wood foundations Insulated concrete forms Free draining membranes and insulations Interior foam insulation systems Framing1940s 1960s 1980s 1980s, 1990s 2000s Platform framing Pre-cut studs New framing options; some use of prefabricated panels; introduction of pneumatic nailing and cordless power tools, ’House-as-a-system’ concept Increased use of trusses and composite materials Increased use of engineered wood products and advanced framing details9 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION AreaPracticeAdvancement or trend Roof1940s 1960s 1980s 1980s, 1990s 2000s 2010s Laid out and constructed by skilled trades Engineered, prefabricated trusses in general use New truss designs available, little change in process Increased use of clay or composite tiles Increased availability of longer warranties and materials with recycled content Introduction of fibreglass shingles Sheathing1940s 1960s 1980s 1980s, 1990s 1980s, 1990s 2000s 2010s Boards Fibreboard and plywood sheets Waferboard sheets, insulative sheathings, use of pneumatic nailing tools Common acceptance of insulative sheathings, OSB sheathing Common use of house wrap air barrier materials Development of materials with variable vapour permenace Increased use of exterior insulation to reduce thermal bridging Siding1940s 1960s 1980s 2000s Wood clapboard, brick, stucco Pre-coated aluminum, steel and hardboard Vinyl siding Fibre-cement siding, advanced weather details (rainscreens), improved flashing details Plumbing, Heating and Ventilation 1940s 1960s 1980s 1980s, 1990s 1980s, 1990s 1980s, 1990s 2000s 2010s Site-fitted and installed Prefabricated chimneys, some ductwork sub-assemblies Plastic plumbing, prefabricated chimneys and flues, energy-efficient equipment, mechanical ventilation systems, electronic air cleaners and power humidifiers Broader acceptance of balanced mechanical ventilation systems Integration of components of mechanical systems (HRV/ERV) Broader use of ground source heat pumps Increased awareness and use of water-saving fixtures Increased use of radiant floor heating Concept of net-zero energy use. Updates to Standard for sizing mechanical systems to better address low-load housing Net Zero Homes built, cold-climate air source heat pumps in use Interiors1940s 1960s 1980s 1990s, 2000s Wet-finished with plaster, cured, brush-painted Dry-finished with drywall, roller-painted Little change, some use of spray-paint equipment Low-emissions finish materials (paints, flooring and cabinetry) Windows, Doors and Cabinetry 1940s 1960s 1980s 1980s, 1990s 1990s, 2000s Fabricated on-site Prefabricated windows, cabinetry, and countertops Sealed thermal windows, insulated metal doors, pre-hung doors, prefabricated stairs, modular cabinets Super windows comprising low-E, gas fill; insulated spacer, low conductivity frames Lower-emissions materials and finishes10 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION In 1993, ten Advanced Houses were built across Canada. Each was designed to be twice as energy-efficient as the R-2000 requirements at the time. The houses also met strict environmental and indoor air quality criteria. The Advanced Houses were built as part of a joint government and industry initiative to provide a showcase for research and development of innovative housing products and technologies. Extensive monitoring was part of the program. Some of the successful technologies became part of mainstream housing construction. Building on the success of the Advanced Houses, new criteria were added to the R-2000 Technical Requirements in 2000 for indoor air quality, environmentally responsible materials selection and construction practices. These changes once again placed R-2000 at the forefront of Canadian home building. New homes are increasingly incorporating healthy house features for improved indoor air quality and enhanced occupant comfort. These features build on the research, development and demonstration initiatives of Canada Mortgage and Housing Corporation (CMHC). The Canadian Centre for Housing Technology (CCHT) research facility was established in 1998 at the National Research Council’s Ottawa campus to advance the development and market acceptance of technologies and materials to improve the safety, comfort and energy efficiency of housing. CCHT is a joint venture of NRC’s Institute for Research in Construction, Canada Mortgage and Housing Corporation, and Natural Resources Canada. In 2015 construction began on an expansion of the CCHT to include 2 Net Zero Ready, semi- detached, smart homes to evaluate low energy solutions and technologies for the multi-unit market. In 2012 CMHC coordinated the development of 12 EQuilibrium Housing projects (net-zero housing). This was a national program that brought the private and public sectors together to develop healthy homes that produce as much energy as they consume on an annual basis. The EQuilibrium homes focused on the core principles of occupant health and comfort, energy efficiency, renewable energy production, resource conservation, reduced environmental impact and affordability. Within the past decade, a number of environmental labels for houses have entered the Canadian market. All of them include energy efficiency as a key element based on the building practices pioneered by R-2000 and described in this manual. In 2012, the R-2000 standard was updated, making 2012 R-2000 homes twice as energy-efficient as before. The EnerGuide for New Houses labeling is being encouraged for all new houses and EnerGuide ratings for existing housing is also being supported by the CHBA. At the time of updating this manual, CHBA had formed a Net Zero Energy Housing Council, developed Net Zero Technical Requirements based on the R-2000 Technical Requirements and the EnerGuide Rating System. Hundreds of houses have been labeled as Net Zero and Net Zero Ready. 1 .2 Features of Quality Housing Houses built using the construction techniques described in this Manual share several characteristics: • Cost-effective insulation levels; • Airtight building envelopes; • High-efficiency heating and cooling systems that are appropriately sized; • Appropriately sized, user-controlled, balanced mechanical ventilation systems; Efficient use of energy, water and resources; • High-performance windows; • Healthy and resource-efficient building materials; • Environmentally responsible building practices; and 11 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION • Use of appropriate on-site renewable energy. These characteristics result in value-added performance attributes: Greater Comfort An airtight building envelope reduces air leakage, thus eliminating uncomfortable drafts and reducing dust, insects and outside noise. At the same time, enhanced control of ventilation air and indoor humidity levels allows improved occupant comfort. Healthier Indoor Environment Appropriately sized, user-controlled, balanced mechanical ventilation systems exhaust stale air and replace it with fresh outdoor air. The fresh incoming outdoor air is preconditioned by the outgoing stale air. It is then mixed with indoor air, heated or cooled to a comfortable temperature, filtered when necessary, and distributed throughout the house. The selection and use of materials with reduced toxicity and mechanical equipment that minimizes the potential for spillage of combustion gases are additional means to ensure a healthier indoor environment. Better Energy Efficiency Higher insulation levels and lower air leakage rates keep heat loss to a minimum and enhance comfort. Efficient mechanical systems reduce the energy required for space conditioning and water heating. In addition, efficient lighting systems and appliances further reduce energy needs. More Durable Construction Proper construction details reduce moisture- and weather-related problems that can cause premature deterioration of structural components and interior finishes. A well-built home requires less maintenance and repair, and retains its value better. Less waste material is generated due to repair and replacement. Improved Resource Efficiency Fixtures that reduce the use of water, electricity and construction processes based on the “3 Rs” (reduce, reuse and recycle) of waste management, in conjunction with energy efficiency, all lessen the effect of construction on the environment. 1 .3 The House as a System At one time, designers and builders often considered each part of a building including; foundation, floors, walls, roofs, windows and doors, plumbing and electrical systems, heating, cooling and ventilation systems- individually. Today, builders recognize that the various parts of a house work together as a system to create a comfortable, durable and energy-efficient building. The house system itself interacts with both its surrounding environment and with its occupants. The climate and environment of where the house is located plays an important role. As well, there are a number of components within a house that have an effect on the performance of the overall system: • The external environment such as temperature, wind, rain, air quality, dust, and noise; • The occupants, including pets; • The building envelope, including the foundation and above-grade walls, windows, roof, and floors; • Interior fixed components such as partitions, floors, and finishes; • Appliances, equipment and furniture; and, • The mechanical/electrical system including heating, ventilating, air conditioning, plumbing and electrical components. The individual characteristics of these components and the way they interact affect the performance of the house as a whole, in terms of the: • Protection provided from the external environment; • Service connections to municipal or on-site water and sewer; 12 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION • Usability of spaces and components within the home; • Quality of the interior environment including the balance of natural and electric light, noise levels, air quality, temperature, humidity, dust levels, etc.; • Durability/longevity of the house and its sub-systems; • Energy performance; • Capital and operating costs; and, • Character and ambiance. The concept of a house as a system is best illustrated with two examples. 1. Supplying fresh air was once considered to be simply a matter of opening windows. Air only moves when there is a pressure difference so wind was needed to drive the process. However, it was highly inefficient because fresh air entering the window did not mix well with the rest of the air in the house. 2. When mechanical exhaust systems were introduced into houses with naturally- aspirating, fuel-fired furnaces and water heaters they were regarded as totally separate components, independent of any other element or appliance in the house. This perception led to intermittent problems in some houses, as the action of exhaust fans caused back-drafting of the furnaces and/or water heaters, resulting in combustion gases to be drawn into living spaces. Today, there is an understanding that the interaction of the sub-systems in a house affects indoor air quality. The tightness of the envelope determines the degree to which air infiltrates or exfiltrates. The cooking, laundry and washing habits of the occupants affect the production of moisture and the need for air exchange. Environmental factors such as location, exposure, wind speed and direction, can affect heating, cooling and ventilation needs. All these factors influence the design and operation of mechanical sub-systems. The best way to provide comfortable, safe indoor air conditions for the occupants is by constructing a well-insulated, tight building envelope, provide energy efficient mechanical systems and using controlled, balanced ventilation. 1 .4 How to Use this Manual A house is a complex interaction of many design considerations. Each is important, and needs to mesh with the others. The theme of the house-as-a-system underlies the organization of this Manual as shown graphically in Figure 1.1. Part 1—House Design (Chapters 2 to 5) covers the basic principles of building science and design which underpin the solutions described in later chapters. Part 2—Building Envelope ( Chapters 6 to 14 ) deals with the foundation, floors, walls, ceilings and roof, windows and doors, and describes various ways to ensure that the building envelope is airtight and has optimum insulation levels. This section also addresses the selection and proper installation of windows and doors. Part 3—Mechanical Systems (Chapters 15 to 23) covers mechanical and home automation systems, with information to help builders determine the most appropriate type of equipment, and to provide a level of understanding to allow builders to discuss mechanical system issues with specialized subcontractors. Manufacturers and distributors can provide more detailed information on specific products or particular installations. Chapter 24 provides predictions into the future of housing and house construction.13 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION This edition of the Manual makes reference to both printed and online information. Website links provided are solely for reference; the Canadian Home Builders’ Association does not control or necessarily endorse the content on these websites, and recognizes that the information available may change or be removed.This Manual also contains an index and several appendices. These include tables indicating the permeability and insulating values of building materials, common conversion factors, and a glossary. New to this edition of the Manual are additional appendices which are available online. In some cases, these appendices represent information which we expect will be of interest to a subset of builders and designers specializing in specific areas of housing technology such as zoning of heating systems. In other cases the decision to put an appendix online was to allow users to have the most up-to-date information on topics such as the Net Zero Technical Requirements. For all appendices available on line CHBA will be updating these if changes are made by their respective authors. Figure 1 .1 Builders’ Manual contents Part 3 Mechanical systems 15. Principles of Space Conditioning 16. Heating Systems 17. Heat Distribution Systems 18. Ventilation Systems 19. Cooling Systems 20. Domestic Hot Water Systems 21. Mechanical System Sizing 22. Renewable Energy 23. Home Automation 24. Future Gazing Part 2 Building envelope 6. Air, Weather, Moisture, Thermal, Vapour and Termite Barriers 7. Materials 8. Air Barrier System Construction 9. Foundations 10. Floors 11. Walls 12. Attics and Roofs 13. Windows and Doors 14. Factory-Built Housing Part 1 Building design 2. Building Science 3. Design Considerations 4. Indoor Air Quality 5. Housing and the Environment14 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION 1 .5 Updates to the Builders’ Manual This Manual has been reviewed by selected technical advisors and builders to incorporate the latest materials, best practices and code requirements. Figures and text have been revised and updated to reflect changes to the 2015 National Building Code of Canada. Chapters have been edited to include aspects of Net Zero Energy Housing. New Chapters have been added on Sizing Mechanical Systems and Future Gazing. In addition, the Builders’ Manual is taking advantage of technology and selected Appendices are only available on-line. This allows us to keep the Appendices up-to- date, and it allows users to contribute and to comment. Also, for the first time, CHBA will making architectural details available for download with the intended result of having architects and builders use them in their plans. Drawings are in 3D – a direction the industry is expected to be moving. 1 .6 Net Zero and Net Zero Ready Introduction For several decades, continual advances have been made to reduce the heating, cooling and energy used by housing to minimize expenses for home owners and to conserve non- renewable energy sources. This Manual presents the concept of Net-Zero Energy Housing (NZEH) and the goal of constructing housing that has no net annual external energy demands. It describes features, benefits and lessons learned from the design, construction and operation of Canadian low-energy and NZEH houses. A net-zero energy house generates as much renewable energy as it uses over the course of a year. A net-zero ready house has all the building envelope and energy efficiency measures as a net-zero energy house, but does not include a renewable energy system. House orientation, sufficient roof area and ideally, pre-wiring for easy installation of a future renewable energy system are part of a net-zero ready house. Net Zero Energy Housing Projects In Canada In 2005, Canada Mortgage and Housing Corporation (CMHC) initiated the EQuilibrium™ Sustainable Housing Demonstration Initiative to provide a national showcase of market ready, near- and net-zero energy housing solutions in regional markets and climatic conditions across Canada. The goal was to demonstrate that the knowledge and technology was available to create cold-climate, high-performance housing solutions, and to start a continuous learning environment for improving the process and cost of achieving NZEH performance. By the end of 2011, eleven demonstration houses (new and retrofit) had been built across Canada ranging from the mild climate of Vancouver to the cold climates of Winnipeg and Edmonton, targeting near- and net- zero energy consumption. Interest in Net Zero grew among Canadian builders and CHBA recognized that these forward-thinking entrepreneurs needed a place where they could meet and discuss the issues around building and selling these types of houses. CHBA created the Net Zero Energy Housing Council in 2014 to provide support for members wanting to work together on this. CHBA now runs a labeling program through the Net Zero Energy Housing Council to recognize these builders and these homes. The logos for these two housing products are shown below (Figure 1.2). Figure 1 .2 Net Zero Logos15 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION Net Zero Ready and Net Zero Energy Housing offers the following advantages: Consumer benefits • Low energy bills; • Improved comfort; • Healthy indoor environment; • Quality design and construction; and • Energy security Societal benefits • Reduced pollution and CO2 emissions; • Reduced demand on urban infrastructure (energy, water and wastewater); and • Energy security. Features of Net Zero Energy Housing The Housing demonstration projects and the pioneering work done by CHBA members is showing that net zero ready and net-zero energy housing can be built in a range of housing styles and forms (new and retrofit; single- detached, semi-detached, and multiple unit) on urban, suburban, and rural sites and in a range of climate zones. These houses share many common features (all of which will be reviewed in detail in this Manual) as follows: Building systems • Site- and climate-specific integrated design solution; • Highly advanced building envelope comprising high levels of insulation, careful selection of windows based on thermal resistance and solar heat gain characteristics and air sealing that results in a low air exchange rate (1.50 AC/hr or better); • Passive solar design strategies; • Reduced domestic hot water usage; • Reduced mechanical, lighting and appliance loads; • Properly sized, high-efficiency mechanical systems; • Heat recovery (from exhaust ventilation and waste water); and, • Utility grid connection to exchange (buy and sell) energy. The airtightness of projects done ranges from 0.4 to 1.4 AC/hr. Careful design and construction is required to achieve low air leakage rates. Blower door testing (see Figure 2.4) is used to measure the air leakage rate. Renewable energy components • Passive solar heating and cooling; • Solar domestic hot water system; • Earth energy or active solar space heating system; and, • Solar photovoltaic or wind turbine electricity generating systems. Iterative design process features • Energy performance modeled and tested (repeatedly); and • Continual validation of the cost/benefit of additional envelope improvement versus the cost of providing alternative energy capacity. • Optimization of house design to account for window placement/performance, location of solar panels16 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION The basic principles for Net Zero Ready and Net Zero Energy Housing are: • Minimize heat losses through the building envelope with appropriate amounts of insulation, a high degree of airtightness and the use of windows with high thermal resistance and a low solar heat gain coefficient. The low solar heat gain is to reduce cooling loads in the summer in those areas of the country that typically need cooling. • Use energy efficient lighting, appliances and minimize exterior energy use thereby reducing the base loads as much as possible. • Use the most efficient types of space heating, water heating and ventilation systems available. This may include such measures as a drainwater heat recovery system for the DHW system. • Provide the house’s supplemental energy using a renewable energy source. Lessons Learned So Far Lessons learned in overall design Keep the design of the house as close a possible to conventional house design. This reduces the cost and delivery time of components such as windows. The objectives of the overall design should be stated and written out in advance to help avoid “design creep”; adding elements to the design which are tangent to its overall purpose. Elements in the house should be off-the-shelf, or at least commercially available. While orientation of the house to take full advantage of solar photovoltaic energy generation is always an objective, it is often not possible. The house should be designed with adjacent architecture in mind. Cost is always an issue. While there are extra costs associated with innovation, cost/benefit should always be an issue in deciding any feature in the house. Sometimes, choices are constrained by the homeowner himself (“I can get a deal”). Reducing air leakage is critical in Net Zero Energy Housing or Net Zero Ready design and construction. Therefore, avoid or plan around known problem areas such as attached garages, 1-1/2 storey kneewall intersections, irregular-shaped protrusions or cantilevers; be wary of three-sided intersections and suspended basement floors. Also, recessed lighting, fireplace chases and duct penetrations, especially for solar systems, need particular attention to air tightness details. For air tightness, focus on the big leaks and the top of the building. Air leakage increases with building height. Complicated details should be drawn out in the house plans, and an air tightness test should always be done. Depending on the air barrier approach chosen, it may be possible to test during construction to allow any air leaks to be corrected before the house is finished. Lessons learned in energy modeling Overheating can become a concern in very well-insulated buildings, and modeling cooling loads is a vital step in assuring occupant comfort. Overheating is usually localized, and there is no reliable modeling tool to predict over heating. Thermal mass is sometimes a component in Net Zero Energy Housing design, but it has limitations. Thermal mass is all about cycling a large mass through a (usually very small) temperature range. Big mass can be expensive (concrete costs up to $200 per cubic meter), so ensure modeling takes into account the cost of adding mass against the energy savings, which often are not significant.17 CANADIAN HOME BUILDERS’ ASSOCIATION CHAPTER 1 — INTRODUCTION Lessons learned in window selection With the increased levels of insulation and excellent air tightness being used in Net Zero Energy Houses, passive solar can be a critical design element. Over-heating in the summer is the issue, which adds to the cooling load. As a result, the lesson learned is to select a window which has a high insulation value to reduce heat loss in winter, and a low solar heat gain coefficient to reduce heat gain in summer. If the window is selected to limit solar heat gain in summer, then it also limits the heat gain in winter. However, it appears that more energy is saved by reducing the cooling load than is collected in winter. The decision of allowing heat gain vs limiting heat gain is very dependent on the location of the house. If the house is in an area where summertime cooling is common, the low solar heat gain is likely better. If the house is in a location where summertime cooling is not used, a higher solar heat gain coefficient will be a benefit by allowing more passive solar heat gain in winter. Lessons learned in energy and mechanical systems Solar (PV) energy production may be less than first calculated due to snow cover on solar panels or, worse, the sun being blocked by surrounding trees. Also, a significant part of the solar system may be facing the wrong way because some of the roof may not have the proper orientation. Available total roof space is a limiting factor in Net Zero Energy Housing energy production. It’s very easy for the mechanical system to become too complex. Control your ambitions when it comes to trying to seize every thermodynamic opportunity. In demonstration houses, dehumidistats failed to provide adequate control over indoor relative humidity. Control systems overall are a huge challenge. Controls can easily become too complicated, and control systems from different manufacturers may not interface and cause later problems with maintenance and warranties. The mechanical equipment itself may not behave as predicted or one element may interfere with the operation of another. For example, does pre-heating service water using a solar system prevent the water heater from firing because incoming water is warm enough that it never hits the set-point? HRVs and ERVs do not come standard with highly efficient motors. And just how much space is required by the mechanical system? 1 .7 Suggestions for Further Information The references listed here are general in nature and apply, to varying extents, to most or all of the chapters. Canadian Home Builders’ Association 141 Laurier Avenue West, Suite 500 Ottawa, ON K1P 5J3 Phone: (613) 230-3060 Website: http://www.chba.ca General Email: chba@chba.caNext >