Since 2006, Midcoast Green Collaborative (MGC) conducted hundreds of independent energy audits, each one a mutual learning experience. The audit reports recommended actions to improve the energy efficiency of the house. Those actions were well worth taking if they cost less than 7 times the projected annual savings, based on the fuel price at the time of the audit, even if funds for them had to be borrowed.
After an independent energy audit there is no sales pressure and the home owner is free to follow or ignore the audit report’s recommendations. He/she can decide to spend or not spend part of what heating oil costs on permanent improvements instead. The right choice has been paying off spectacularly for some of our Midcoast Maine neighbors. In these columns I plan to explore several examples. To protect homeowner privacy, I only identify each house by a Greek letter, without revealing visual features or location.
Alpha house has two occupants and a heated floor area of 2820 square feet. At the time of the audit, the house was fairly leaky, with almost half a natural air change per hour. It burned 1300 gallons of oil annually for heating, at a cost of $5,187. The 5,522 kWh of electricity the house also consumed cost $848, for a total energy bill of $6,035 per year. The energy audit report projected 42% potential first year energy savings ($2,060), provided the following recommendations were followed:
- In the fall, remove all bug screens, which reduce passive solar gain by as much as 30%. Close and latch all windows during the heating season. Keep basement windows and crawl space vents closed at all times.
- Reduce water heater temperature to 120ºF. Check the sacrificial anode rod of the hot water tank, replace if necessary. Periodically release some water from the bottom spigot to remove sediment. Wrap the tank in an insulation blanket. Wash clothes in cold water, with proper detergents they will get just as clean.
- Extend the existing plastic sheet on the crawl space floor up the foundation wall. Seal the sheet to the wall. Vent the dryer outside and removed the lint often from its outlet.
- Insulate the hot water pipes in the basement with at least 5/8” thick ozone friendly foam pipe insulation.
- Safely reduce air leakage by 22%, staying within ASHRAE guidelines, without the need for added ventilation, or install heat recovery ventilation (HRV) and continue air sealing. Every square inch of the equivalent leakage area of 218 square inches (1.5 square feet) that can be plugged for less than $33.61 is worth sealing. In addition to the locations marked with painter's tape during the audit, seal all penetrations of the attic floor and the basement ceiling, (best done with spray foam). Seal all electrical outlets and switches with foam gaskets and child-safe plugs.
- After air sealing the attic floor, add a vapor barrier, followed by insulation up to R-60.
- Insulated surfaces should have a vapor barrier on their warm side. The easiest way to add this is by means of shellac-based vapor barrier primer paint, such as BIN, on top of which a choice of finish coat(s) may be added.
- Install interior storm windows, available finished, as kits, or made at home from instructions on the www.midcoastgreencollaborative.org web site. Make sure the storm windows cover any metal window frames.
- Weather-strip outside doors, the door to the basement and the hatch to the attic, all of which should close firmly against a jamb.
- Install storm doors. Cover doors not used in the winter with insulation or at least heat shrink plastic. Insulate and seal the bulkhead door tightly.
- Set thermostats down several degrees while sleeping and when away. Save up to 2% of your heating energy for every degree of setback.
- Replace incandescent light bulbs with LEDs. These are very efficient and last longer, because they generate very little heat. Eliminate or reduce phantom appliance loads. Standby-mode and plug-in transformers use electricity even when the appliance is “off”. Use a power strip, and switch it off when such loads need not be on. Turn off computers when not in use.
Had they chosen not to act, the owners of Alpha house would have spent more than $32,380 on heating alone since the audit. In contrast, an investment of $9,500 to implement the audit’s recommendations saved them $13,601 over the past 7 years -- a net savings after expenses of $4,101. Looking ahead, compared to having done nothing, these home owners can look forward to saving at least $2,000 off their annual heating bill, year after year.