greenspree.ca at The Sietch

One thing I run into time and time again as an energy efficiency adviser is lack of consideration of a house, or any other building, as a system. Buildings are a complex arrangement of systems not totally dissimilar to biological ones. And what one does to one system in a building can positively or negatively impact others.

Let me give you a few examples:

1. A family lives in a trailer park in a 20 year old mobile home. They are concerned over their rising electricity costs but don’t have a lot of money to spend on upgrades so they take a cue from their utility companies advertising and switch the 12 incandescent bulbs in their home to energy efficient CFL’s. They expect to save about $10-15 a month on their light bill as all the literature on the CFL packages and the utility companies brochures promised, instead it barely changes, maybe lowering $2-3 a month. What happened? They heated their home with electric baseboard radiation and once they replaced their incandescents with energy efficient CFL’s they lost the by product of the inefficiency, heat. Incandescents produced light from 5% of the electricity they use, 95% of the rest is emitted as heat. So light bulbs are 95% efficient electric heaters in essence, and if you are heating with electricity the savings in your light bill you would have had by using CFL’s are mostly eaten up by increased demand for heat on your resistance heaters.

2. Family number two has an old farm house that leaks a lot of air, and heat, due to having no air or vapour barriers and aging building materials. They also have an inefficient furnace and want to reduce their reliance on it. They decide to install a new pellet stove and replace the old wood shingle exterior with new styrofoam backed vinyl siding to add another layer of insulation to the house and reduce air leakage. They also add an airvbarrier to the exterior of the walls. They have the work done in the summer and have no problems until colder weather sets in. The air quality seems to be getting worse and worse! Turns out the new pellet stove and the old furnace are using up a lot of oxygen in combustion air and the not so well sealed furnace is leaking some exhaust fumes into the house! Before when the building was drafty this wasn’t a problem as there was a lot of natural ventilation and fresh air entering the building. What the home owner’s failed to consider was that a newly air tight home needs to have some form of mechanical ventilation and fresh air intake. An energy efficient heat recovery ventilator (HRV) should have been installed.

3. A family with an large old town house has an ancient oil fired boiler and large drafty windows. They decide to replace the furnace with a new high efficiency unit, they see savings and decide to continue their upgrades, the replace or weatherstrip their old windows, add insulation to their basement and tighten up the exterior. They soon discover that with their new tight home that the new boiler is now grossly over sized for their needs and not working at it’s peak efficiency, they also have spent money needlessly on the boiler when a smaller capacity one would have sufficed if they had done their insulation work first.

There are many many more examples, some much subtler though they still need to be considered when doing any renovation to your existing home. So before you start your next reno, stop and consider how it will impact the other parts and systems in your house, consult and expert if required and make sure you are being as efficient and pro-active as possible!