The original natural family living magazine, founded in 1976. Reader-supported
and trusted by thinking people around the world who want positive alternatives
to high cost, high consumption lifestyles for themselves and their families.
|
|
|
||||||||||||||||
|
from Natural Life magazine,
March/April 2009 Part Four: Energy And Atmosphere This decade has seen an emphasis on energy savings and how to seal up our homes, install high efficiency equipment and change light bulbs. Yet, despite the importance of these fundamentals, many of us know that there is much more that can be done. The good news is that the Canadian residential version of LEED™ – Leadership in Energy and Environmental Design is being released this Spring and, with the inclusion of Net-Zero Energy Homes (NZEH), even more savings will be demonstrable. In this issue’s column, I am providing an overview of how the construction market is adapting to become more energy conscious. I hope that, as a home owner or someone who plans to build or buy, it will help you be more knowledgeable about what to ask a developer or a builder. You will notice how energy saving is linked to the overall construction process and not only to window quality and other obvious considerations. Energy saving is also closely linked to indoor air quality; the importance of maintaining a balance between air quality and energy consumption will be the subject of a future column in this series. Optimal Energy Performance For a house to be LEED-certified, specific requirements called Prerequisites must be met. In this category, a home must reach at least a 25 percent reduction in energy consumption, which is the same as being rated as ENERGY STAR®. For example, if the average 2,000-square-foot home uses 40,000 kWh of energy per year, a LEED certified home would use no more than 30,000 kWh. Any mention of saving is in reference to this base value. Of all the points and credits that the LEED certification system awards to a builder’s efforts to build a sustainable house, this category earns only 28 percent, which stands as evidence that sustainability is not just about saving energy. Insulation This is simple: a LEED certified residential building must exceed code R-value requirements by five percent. Air Infiltration Simple again. Have an air leakage test performed by a qualified rater and meet the specified requirements. This test verifies the quality of construction in terms of sealed wood joints as well as around openings through the envelope, such as windows and vents. Windows Manufacturers tend to mislead consumers in their presentation of R-values. It is important to know that, typically, the glass portion resists transfer of energy more than the frame. Therefore, a true R- value should include the entire unit. Some tips for increased R-value are: more space between the panes of glass, three panes are better than two, no dividers or other accessories between the glass. Also, decrease the openable perimeters; in other words, don’t install a window that opens if you never intend to open it. Insulated frames are better than non-insulated, which applies to exterior doors where no insulation is added during installation of the glazing. If a LEED certified house has a skylight, it will be no more than three percent of the total floor space in size. And regular windows areas will not exceed 18 percent of the floor space. When going for LEED certification, the commercial sector is encouraged to position windows to take advantage of passive heating and cooling and to use exterior shading to reduce energy use in summer. I hope the Green Building Council will incorporate the same in the residential guide. Heating/Cooling Distribution Often, residential sheet metal installers are not trained as well as their commercial counterparts and, as a result, poor duct connections become the norm. This results in increased fan energy losses as rooms may not reach their desired temperature soon enough, which impacts on the time the equipment has to run. If the heating system is hot water, LEED certification requires that pipe insulation thicknesses be increased from the normal 12mm to 25mm. Space Heating and Cooling Equipment In the commercial sector, this is where energy savings can exceed 50 percent; homes can far exceed that percentage. For instance, radiant floor heating (RFH) systems can account for a 15 to 25 percent decrease in energy use when installed properly, with 50mm of insulation below the floor. (Insulation alone will save five percent.) A Heat Recovery Ventilator (HRV) accounts for a one percent reduction in energy use, while air- to-air heat pumps may give 40 percent and geothermal heat pumps may account for 60 percent. So without any real effort, homes built to LEED certification standards can see an 80 percent reduction in heating and cooling demands. For the average home owner, this currently translates to a $1,500 per year saving. The LEED residential certification system gives credit for air conditioning units to be between a 13 and 15 SEER – Seasonal Energy Efficient Ratio – and for heat pumps to be 14 to 19. Average winter temperatures are approximately 60 percent of Canada’s extreme cold days and those really cold days are occasional in most of the country. For this reason, solar heating is a practical solution for meeting average heating needs in that kind of climate. A back-up system is required for the extremes, mainly because there simply isn’t enough roof area to accommodate the panel requirements for those coldest days, with current equipment. Net-Zero Energy Homes (NZEH) apply these principles and, as featured in past issues of Natural Life, there are 12 such homes being built in cooperation with Canada Mortgage and Housing Corporation (CMHC) as prototypes for observation, and many others in other countries. The definition of a NZEH is that it can produce the same amount of energy that it draws from the utilities, thereby balancing its usage to zero. A low number of LEED points is awarded in this space heating and cooling equipment category because much of this technology is already mainstream and part of the intent for the points system is to motivate innovative design and application. Domestic Hot Water This category focuses on distribution as much as heat sources. It realizes that very little care is actually being taken regarding the length of piping used, therefore it places a reasonable maximum of 12m/40ft for the main piping and 3m/10ft for branches. LEED encourages 12mm-sized piping branches with 25mm of insulation, all in an attempt to reduce energy losses. Wherever there are recirculation pumps, they should be on timers or have a switch at the sinks to bring hot water to the faucet and thereby save on water use. The industry has come to terms with solar domestic heating now that the building codes recognize the installations as separate assemblies, therefore CSA approval is possible. As a result, LEED awards credits for a minimum of 60 percent solar hot water. Lighting Imagine taking possession of a new home from a developer and 80 percent of the lighting is compact fluorescent and LED! That is the future. Appliances This category includes ENERGY STAR rated refrigerators, dishwashers, laundry equipments and ceiling fans. I hope that the Canadian version of LEED will emphasize locating laundry facilities close to side entrances where clotheslines will be installed. This will also call on some municipalities to remove restrictions on clotheslines, since advantages to the community are an important part of LEED’s Triple Bottom Line approach. Renewable Energy Renewable energy pertains to electricity production that can be generated from wind, PV solar panels, micro-hydro and biomass. It is realistic for subdivisions to equip individual homes to be able to produce 30 percent of their own power. In the next issue, I will be addressing Materials and Resources, a LEED category that acknowledges the advantages of recycling materials, local purchasing, FSC woods and more. Hugh Perry provides assistance in the preliminary stages of design for sustainable buildings by preparing hand sketches, cost comparisons and answers to the many questions regarding recycled materials, water use, healthy environment, energy and durability. Email him at hughper@gmail.com This is one of a limited number of articles from Natural Life magazine that are available for free. To read all of our current and back issues, subscribe to our digital edition. |
|||||||||||||||||
|
|
|||||||||||||||||
