by Jessica LevinsonWe may finally be seeing hints of winter! I saw my first snow flurry last week and although it melted pretty much before it hit the ground, I think we may be in for some more flakes real soon. The first thing I utter is, “Oh, how beautiful!” followed quickly by, “Wow its cold!”
As winter approaches, heating your house can be costly and an environmental headache for conservationists. There are several ways in which one can make their house green and warmer. In fact, the two seem to go hand-in-hand when done properly.
A fairly new concept in house design combines a third incentive, a healthy home. Passivhaus, Passive House in English, creates a better living environment and can cut energy consumption up to 80%! In Europe, mainly Germany, Austria and Switzerland, they have been using Passive House to build supermarkets, schools, offices and residential areas. This idea has been slowly moving across the pond to the U.S. with businesses and individuals wanting the great benefits that Passive House provides.
The concept of Passive House was first developed as a result of a conversation between two university professors in May, 1988. Professor Bo Adamson of Sweden’s Lund University and Dr. Wolfgang Feist of Germany’s The Institute for Housing and the Environment are the creators who worked to make green homes with healthy air environments.
In 1990 they designed and built the first Passive House row homes in Darmstadt, Germany. Founding the ‘Passivhaus Institut’ in 1996, they have continued to study and design dwellings that are on the cutting edge of environmental friendliness and wellbeing. Their original hope was to design homes with engineers and architects alike that would use ultra low energy for heating and cooling.
An article in the December 26, 2008 The New York Times, interviewed Wolfgang Hasper, an engineer with the Passivhaus Institut about the aim of the foundation. “The myth before was that to be warm you had to have heating. Our goal is to create a warm house without energy demand,” he said. “This is not about wearing thick pullovers, turning the thermostat down and putting up with drafts. It’s about being comfortable with less energy input, and we do this by recycling heating.”
So how does Passive House work? They integrate techniques that have been around for centuries along with new technologies. There are six basic components that are utilized. First, begin with a good insulation. The insulation utilized is thick and installed throughout the house in ceilings, floors and walls. (No asbestos here, please.) All of the insulation is earth and human friendly. This “super insulation” is not, however, air tight. Therefore, the second rule to Passive House is an air tight barrier. The air tight barrier seals over the insulation preventing air penetration between the outside and inside of the home. The third component is designing without thermal bridges. Thermal bridges are found in areas where the manufactured goods are poor insulators and therefore heat can be conducted through area. Although the walls and floors are all highly insulated, the foundation must still be in contact with the ground. What takes place is called a temperature gradient, where heat moves to a cooler area. For this purpose, it is important to use a layer of insulating porous concrete brick. The brick traps the air inside the house and vice versa.
Of course, you can’t seal the windows with insulation. Windows in a Passive House, optimally, are triple paned with two coats of low-e glaze (a film that reflects instead of absorbs). Windows also have a ‘warm edge’ spacer, necessary since there is more than one pane of glass. Lastly, the window frames should be insulated.
So far this is all very unexciting: Basically seal your home so that you don’t have any air circulating. Somehow this doesn’t seem “healthy.” But, here is the really cool part (and probably the most expensive). A mechanical ventilation system!
The system is designed to exhaust old air out and replace it with fresh outside air. Most of us are in homes where the air is recycled; this can be a health issue as well as an energy efficiency issue. Think of how nice it would be, especially in the winter, to not breathe in some one else’s sneeze. So right about now you are thinking, “This sounds good but now I have cold air,” right? Fair enough. But, this new, expensive ventilator actually has a heat exchanger that heats the incoming air with the heat that it extrapolates from the air being ventilated out. They have even taken care to measure which rooms you should exhaust air from (kitchens and bathrooms) and which rooms you ventilate into (bedrooms, living spaces).
Finally the home is finished by an added heat source. This source can simply be the heat exchanger or an additional heat pump, natural gas or biomass fuel. Since the homes are so well insulated, they don’t take much energy to heat (i.e., fuel) making them incredibly green and cost effective (making the ventilator worth the extra moolah).
The only downside, for those mega mansion lovers out there, is the size of these Passive Houses. In The New York Times article, Hasper says that these homes allow for a maximum of 500 square feet per person (that’s 2000 square feet for a 4 person family). His response to those feeling they need more than that, “Anyone who feels they need that much space to live, well, that’s a different discussion.”
“O.K.,” you say, “That sounds really good but it is the middle of winter and I don’t have the funds to build a whole new house.” Well, there are also cheaper ways to make our homes more efficient by retaining the heat we already have. In her book, Ecoholic, Adria Vasil tackles the problem of heating the home on a green scale but not building a whole new house. Many of her ideas follow those same principles in the Passive House (except the ‘healthy’ part, recycled air here).
Many homes loose their heat through cracks and drafts around windows and doors that allow inside hot air to escape and cool air to enter the home. Vasil says that caulking these holes is the cheapest way to make your home more efficient. Next, look to your windows. If buying triple pane windows with two coatings of low-E films is not in the budget, then how about coating your old ones with some low-E film? Vasil says that windows can leak up to 25% of your homes heat, so anything to prevent heat loss is better than nothing at all.
Besides low-E film, she suggests shrink wrap, window quilts, and triple celled curtains, to help limit drafts. One suggestion for these older homes, which you won’t find in the Passive House manual, is on furnaces. Vasil advises buying a new furnace if yours is older than 20 years as it can be 20-30% less efficient than the models out there today. As with any appliance, furnaces need maintenance. She suggests a more aggressive maintenance schedule with said furnace.
“Furnace filters should be replaced or, if you have washable ones, rinsed out, every 3-months at the very least, though once a month is ideal,” she said. “This will come as a shock to the vast majority of us who thought an annual filter change was all that was needed. Sorry kids, dirt buildup here will mean your furnace can’t do its job as well and also has the potential to circulate ‘dirty’ air into your living space.”
Hopefully these tips will keep you warm this winter season. If the Farmers Almanac is correct, we should be headed for a colder than normal winter. If not, and we find ourselves with tropical weather, don’t fret. These techniques help keep a home cool in warm weather as well!