There are a number of different construction standards for low energy homes in Canada: ·EnerGuide Rating
·R2000
·Energy Star for New Homes
·LEED for homes
·Built Green
·PassivHaus
It makes a lot of sense that a smaller home built to the same standard will be more energy efficient than a larger home. Larger homes generally use more energy to heat and cool. This energy usually comes from the combustion of fossil fuels emitting greenhouse gases into the air.
Also, larger homes use more material for construction.
A home should be just the right size for its occupants and their activities. Giving thought to how to reduce the size of your home will reduce construction costs and the amount of energy you use.
The best way to orient a home is with its long axis running east to west. With this orientation, the longest side of the home faces south. The south is the sunniest direction and hence the warmest, so orienting a building this way maximizes solar heat gain.
In Canada, the sun is quite low during the coldest months when you need it most for heating. As such, it is important to consider the location of evergreen trees, neighboring homes, etc to the south of the home.
Passive design is an approach to building design that uses architectural design to reduce traditional energy consumption and provide thermal comfort to the home. Passive design is very specific to the location of the home in terms of climate, orientation, etc.
Passive Solar is one of the most cost effective methods of heating a home. A key element of passive solar design is the use of south facing windows. This 'south window to heated floor' ratio is critical to successful design.
The building envelope is the exterior surface of the building and includes the foundation, walls, windows, doors and roof. The building envelope is made up of the following elements:
·Interior finish
·Air barrier
·Vapor barrier
·Structure
·Insulation
·Rain shield
·Exterior finish.
Also worth looking at is this excellant interactive graphic by Fine Homebuilding that explains thermal bridging.
One of the construction techniques pioneered by Rob Dumont and used in many of the EQuillibrium homes is the double wall construction with cellulose fibre insulation.
Structural insulated panels (SIPs) are high performance building panels used in floors, walls, and roofs for residential and light commercial buildings.
Insulated concrete forms are rigid plastic foam forms that hold concrete in place during curing and remain in place afterwards to serve as thermal insulation for concrete walls.
There are a number of commonly used insulation materials. The choice of the most appropriate material is usually determined by the cost and the application.
The typical R Value for attics in EQuillibrium home construction is R 100. Using batt or loose fill insulation, this will require 27 to 30 inches (100/3.7) of insulation.
Windows are a key element to every home. They are often a key part of the architectural design of a home. Windows are a source of light, passive heat and ventilation. Poorly designed windows can cause overheating in the summer and cold drafts in the winter. Windows affect both indoor living comfort as well as Energy savings.
Air leakage can account for 30% or more of heat loss in residential homes. Reducing air leakage will reduce energy usage but air change in homes is needed for healthy living. This section will cover the use of air barriers to properly seal a home to reduce heat loss. The section on ventilation will cover requirements for air change.
CMHC in their report ‘Design Guidelines for Green Roofs’ (Canada Mortgage and Housing Corporation, 2005) define green roofs as ‘ a green space created by adding layers of growing medium and plants on top of a traditional roofing system. Green roofs have been around for hundreds if not thousands of years. Although relatively new to North America, green roofs have been accepted in Europe for some time. Older residents of the Canadian prairies will remember the sod hut construction of many homes of early settlers.
Ventilation is the exchange of indoor and outdoor air. Natural ventilation is exchange of air without the use of fans. Mechanical ventilation is air exchange created by fans.
Improving the quality of the air barrier will result in a much tighter building envelope. This reduces the fresh air that enters the house through infiltration. More tightly sealed homes will result in improved energy usage but can cause problems with combustion appliances (furnaces, water heaters), condensation problems, or air contaminants.
Homes with a high quality air barrier will require mechanical ventilation systems. In the cold of winter, this involves bringing cold outside air into the home and will result in higher energy costs. Heat Recovery Ventilators (HRV’s) are air-to-air heat exchangers. They transfer the heat energy from warm stale air to the cold fresh air entering from outside.
Drain water heat recovery (DWHR) is a relatively simple technology to reduce household hot water energy consumption and to prolong the availability of hot water during periods of high demand or continuous use.
The earth’s temperature remains at about 10 degrees Celsius all year around. That means the earth can be a source of heat in the winter and a source of cooling in the summer.
There are four main types of Solar Water Heating Systems. SWHS can be either active or passive. Active systems use electric pumps to circulate fluid through the collectors. Passive systems have no pumps and rely on thermo-siphoning to circulate water. SWHS can also be classified as open-loop or closed-loop. An open-loop system circulates potable water through the collector while a closed loop uses glycol and a heat exchanger to transfer the heat to the potable water.
Looking for a place to build green? There are a number of subdivisions in Saskatchewan that support green home construction. Click on [details] for more information.
