Coming in out of the cold, a phrase currently more relevant than usual to those of us experiencing unusually chilly weather, means having a house. It might be an apartment, a condo, a town home, a duplex or even just a tent but human beings need a place to get out of the elements and our houses serve this among other purposes. Next week I'm going to talk about all the other systems functioning our homes but this week the focus will be on home heating, the single largest component of residential energy used.
Residential energy accounts for 21% of US energy Usage. Of that, one third is devoted to space heating. The numbers in total for residential usage look like this.
32% space heating
13% water heating
11% air conditioning
5% wet-clean (mostly clothes dryers)
So while it is important to pay attention to the amount of energy used by our fancy new electronic gadgets , the lowest hanging fruit in terms of energy conservation turns out to be a reduction in amount of energy we use to heat our houses.
The bad news is that many of the homes constructed in the post WWII build out are incredibly inefficient. Energy for home heating was and relatively speaking, still is cheap (if you don't count the cost of a changing climate) and so the traditions of vernacular architecture, site specific design and secure construction techniques where thrown out a drafty window.
The good news is that this represents an opportunity to greatly reduce the amount of energy used in the United States without having to address supply issues at all. It also represents an opportunity for individuals and families to make themselves more financially secure by lowering their home heating costs. Right now the costs associated with the resources we all use are relatively stable but in an energy constrained future those costs will not only increase, they will become volatile as a market used to dependable growth in resource availability clambers to cope with the reality of energy descent. Paying attention only to the financial costs, priced in today's dollars, of addressing our energy needs could leave a lot of people out in the cold.
More good news comes from the fact that some of the steps we can take to make our homes more energy efficient in terms of keeping the insides warm are relatively cheap. Most of us live in homes that have an HVAC system (Heating, Ventilating & Air Conditioning) that sucks too much air in from outside when doing the job of keeping our homes warm. This problem can be addressed with a caulk gun and a candle. Turn on your HVAC system and light a candle. Now carefully move the candle around the window frames and door frames of your home. The disruption of the smoke will smoke will let you know where you have leaks. Of course a smoke puffer is a bit safer and less messy than a candle and not that expensive.
Or, for a very reasonable amount of money you can hire a professional to do a blower door test. A special door insert uses a fan to put negative air pressure in your home, causing it to suck more air from outside than normal. This makes air leaks easier to detect. You can also use the blower door to make sure you have sealed your home to an appropriate tightness.
Now, you don't want an air tight house. That would be like living in a sealed plastic bag. Interior air quality would suffer and with it human health. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has set standards for the amount of inside air that should be replaced with outside air on an hourly basis. You're not likely to over seal your home using a candle and a caulk gun and the professionals that might do a blower door test will understand these standards.
Also don't forget about one of the single largest air leak in many homes, the attic door! Sealing just this leak will noticeably reduce the amount of energy you use to heat your home
Try an Attic Tent.
Proper insulation of floors, walls and ceilings will also prevent heat from escaping and reduce the amount of energy needed to heat a home. My family had cellulose insulation blown into our 1930 brick built home after having is sealed appropriately and saw a significant reduction in the cost of heating. There are lots of options regarding insulation. My advice is to do your own research and then talk with at least one professional who doesn't actually sell insulation about the options for your specific structure. Don't just assume the pink stuff will do.
Insulating a house is more expensive than caulking the window frames but remember to think not just in terms on today's energy costs. We're likely to see an significant increase in the cost of home heating energy in the future that might make the cost of insulating now look super cheap in hindsight.
Once the air leaks and the insulation have been addressed the windows are up next for discussion. Windows let in sunlight which heats up a room. Using sunlight in this manner is called passive solar heating and was once and will again be a standard strategy for architects and home builders.
One problem though is that glass is a poor insulator which means the heat from sunlight let in by the windows can quickly escape. Properly sealed windows will help to reduce the loss. Double or even triple pane windows will help even more by providing a layer of gas (usually argon of krypton) which is a good insulator, between each pane. Having new windows installed in construction or during a renovation will help to reduce the amount of energy needed to heat your home.
There are lower cost strategies as well. My family has installed window blinds and curtains in most of our windows. The blinds help to prevent heat loss at night as do the curtains. There is also a management component to this strategy.
In the morning we open the curtains and rotate the blinds in the kitchen, dining room and other rooms where we spend the morning to let in light. We mostly leave the bedroom blinds closed as they face north and get no direct sunlight. We also don't spend much time in there after we're dressed.
In the early afternoon I pull the blinds up on the south-facing windows to allow the maximum amount of sun to enter into the southern exposure of our home. In the early evening I let the blinds down to help slow down the rate of heat loss but I leave the blinds rotated open to allow light in. As the sun goes down I rotate the blinds closed. This further prevents heat loss and provides a bright white surface that reflects the light from interior bulbs. Before bed I close the curtains to further prevent heat loss. Sound like a pain in the ass? It really just becomes a habit like feeding the dog or walking the cat. And I'm not perfect. Some days it doesn't happen but you can feel the difference and so I try to make this part of my daily routine.
There are more aggressive strategies to limit the amount of heat loss through windows that don't cost a great deal of money. Removable window inserts can be made out of rigid insulation and fabric. These can be placed in windows at night and removed each morning.
Window quilts serve roughly the same purpose as curtains but are used seasonally.
There are window films and other window treatments that can cut down on heat loss while still allowing sunlight and solar radiation in during the day.
A programmable thermostat is an option as well. I tend towards solutions that rely on simpler technology but our programmable thermostat helps us to manage our interior air temperature, making the house more comfortable and more efficient. In general though just turning down (or programing down) your thermostat will greatly reduce the amount of energy needed to heat your home. This is best done by adjusting to the gradually lower temperatures of autumn. It's much easier to get used to 58 degree nights in your house if you do it slowly as opposed to telling your wife that tonight the bedroom temperature will in fact not be in low 70s but rather upper 50s. That's likely to spark rebellion.
On that note I'd like to recommend a cooperative strategy that includes all the members of the household and turns saving home heating energy into a game. My wife, not exactly excited about the insulation of our home during her 6th month of pregnancy, quickly became addicted heat energy reduction. The key was showing her how to track each month using our energy bill and a using a service made available by our natural gas provider. She can compare January of 2008 with Jan '09 and Jan '10 to see how many fewer therms we used *and* how much less we spent post-insulation project to heat our home.
Like any change, reducing the amount of energy used to heat your home is more of a journey than a destination. Set goals for yourself. Create a time line for meeting those goals and away you go.