temperature swings. Metal frames may contain up to 90 percent recycled material, and can be advanta
geous where moisture, termites, or other natural pests are a problem, or where occupants are particularly
sensitive to chemicals used in other products.
Energy Consuming Equipment. Energy consuming equipment in homes and small businesses
include systems such as HVAC, water heating, and lighting.
Many technical opportunities exist to save energy used in HVAC systems. Smarter control systems
could maximize the use of natural ventilation, especially if used with some form of thermal storage.
Controlling relative humidity in air conditioned spaces within the proper range would permit higher air
temperatures while providing equal occupant comfort.
Successful methods are already available to
reduce the large (estimated in the 15 20 percent range) duct energy losses including aeroseal tech
Variable speed air handlers are also available to improve system efficiency and performance.
In the long term, selective water sorbent technology offers the promise of meeting the performance of
ground coupled heat pumps at the cost of traditional systems. Moreover, the sorbent technology inherently
includes a variable temperature energy storage mechanism that can be used to shift electric loads from
peak to off peak times.
Matching HVAC size to the building load has multiple implications for GHG emissions.
Historically, contractors have considered it conservative to oversize HVAC installations, often using rules
of thumb unrelated to any particular house design and especially inappropriate for the newer, more
energy efficient houses. Such oversizing causes units to cycle on and off more often, increasing thermal
losses during each on/off transition. Frequent cycling also reduces occupant comfort, which in turn often
leads occupants to adjust their thermostats to a value that increases total energy consumption. Therefore,
downsizing HVAC equipment to match the reduced requirements of an energy efficient building envelope
can save investment dollars up front and can decrease energy consumption and GHG emissions as well.
Until recently, oil furnace efficiencies above the low to mid 80s were rare. The availability of high
efficiency oil furnaces could significantly affect energy use through installation in new homes or as replace
One manufacturer has developed a condensing oil furnace with an Annual Fuel Use Efficiency
rating of 95 that has overcome sooting problems prevalent with earlier versions of this technology.
Towards a Climate Friendly