A Comprehensive Energy Efficiency Strateg
Energy efficiency is a big topic, and at times a rather convoluted one. It takes energy to heat and light a house, it takes energy to cook and wash in a house, it takes energy to manufacture and transport materials to build a house. So, if you want to create a house with a reduced energy/carbon footprint, there are a lot of ways to do that.
By Mike Reynolds
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Heat Recovery Ventilation [HRV]: Houses need fresh air for the health of occupants, but also to remove moisture for the sake of durability. In this case, replacing stale humid air with pre-heated fresh air is achieved with six Lunos wall insert air exchangers. Lunos is a very different system from conventional centralized HRV systems, as each of the 6 units has its own ceramic core and fan.
Lunos air exchangers work in pairs, one blows in while another blows out. Exhaust air warms the ceramic core, and after about 70 seconds they reverse, so incoming air is pre-heated as it passes though the warm ceramic core. This is said to work at a very high rate of efficiency, around the 90% mark according to manufacturers, which very few other brands can match. By working in pairs blowing air in opposite directions, interior air pressure stays balanced so you are neither forcing warm air out nor drawing cold air in.
Natural lighting: When the sun brings heat, it brings light. The great room living/dining and kitchen area generally requires no daytime lighting except on the darkest of cloudy days. This is an energy saver of course, but also a bit of sunshine makes a long winter easier to endure.
Artificial lighting: All interior light bulbs are dimmable LEDs, provided by Philips. The open concept and lack of interior divisions means less artificial lighting is required.
Appliances: All appliance are ENERGY STAR certified.
Radiant floor heat: Aside from warmth from the sun, we also have a 10-zone hydronic radiant floor [Photo 3] and ‘Radiant Ready’ boiler from Uponor. This topic seems to spur debate among the energy obsessive, with intelligent minds dug in on both sides – do you need a radiant floor or is it obsolete? Can’t you just insulate your way to warm feet? I really think the climate you build in will help answer that question, and ours is very cold. I’ve stood on both sides of that fence and now find myself leaning towards the warm feet side, though there is an obvious redundancy going on when you have multiple heat sources, so let the debate rage on.
Here’s the thing – with a house this well-insulated you really can’t run a radiant floor hot enough to thrill your feet or you would need to open a window to avoid overheating. But at the same time, if your feet are cold you would need to compensate with a higher ambient air temperature to feel comfortable. What we have learned during operation is that the floor is more comfortable if we bring it up just a degree or two, but we intend to use the heat pump to warm the home as necessary.
Air-source heat pump: Heat pumps warm your house not by generating heat, but by compressing it in one location and moving it to another, a much more efficient process. They work like a refrigerator, which doesn’t ‘create’ cold; it condenses heat on one side of an enclosed space and moves it to the other side.
Mike Reynolds is a former home builder, a LEED for Homes Green Rater and the editor of Ecohome.net.