Sunday, December 28, 2008

3. Having a Home Energy Audit

Energy Conservation is likely to become one of the more significant areas of emphasis as the new Administration moves to change the way in which the United States uses energy. One way to lower overall energy consumption is to look at how we each use energy in the course of a day, and then change those habits. Apart from changing transportation habits, one of the more significant impacts is to reduce the amount of energy that we use in heating and cooling our homes. But to find out a) how much we are using and b) how to lower the amount of energy used, we need first of all to do some form of an Energy Audit. Since the lads just had one carried out at their house, I will take a little information from that to describe what might be involved.

The assessment was carried out by a certified analyst who came with a blower door, fitted with a fan that sucked air from the house and vented it outside. This had the effect of pulling air into the house through all the leaks in the walls, etc, so that as time went on, the areas with the greatest leaks became cooler. The first thing that the report mentioned was the amount of air that the fan was removing, this was some 4,120 cfm (cubic feet per minute), and about five times as high as the minimum flow of air recommended for that size building.

The next step in the process was then to find where all the leaks were occurring. The major leak turned out to be in the basement, with the leakage rate dropping by 620 cfm when the door into to basement was shut. This meant that there were significant losses in the basement itself, and a variety of recommendations were made, including 6 mill plastic and foam insulation of the walls, to cut these down to an acceptable level. The house being an old one (in the Historic District) use of these two tools could significantly seal or isolate areas of existing heat loss. As the report noted the rule of thumb is that every square inch of seal emplaced will save the equivalent of 0.5 to 1.2 gallons of oil per year. Foam installation costs were estimated at around $1.00 to $1.50 per board foot (a volume that is 1 ft by 1 ft by 1 inch thick).

Individual leaks around windows and doors were then identified using the thermal imaging camera to show where areas of cold pointed to inadequate sealing. A couple of really high leakage points were found around a couple of the windows, and, depending on size, either caulking or heavier weather stripping was recommended. In cases where the doors did not seal adequately they suggested that the striker plate on the door be adjusted. This should be set so that the door does not move after being closed.

Some of the room images also showed the hot paths of pipes under the floor, which pointed to the relative inefficiency of the under floor insulation, as well as poor lagging on the pipes.

Moving around the house to identify further losses, the report noted that there were a lot of lights that could be made more efficient by changing to compact fluorescents, at about 1/3 of the wattage currently used. They noted that the current refrigerator used between 670 and 737 kWh per year, and the most efficient new ones on the market operate at around 400 kWh. If you assume that the local cost of electricity is around $0.10 per kWh this is an annual saving of around $30 a year. Actual use and savings would, however, depend on the amount of use the different appliances used, and recommended getting a kill-o-watt type device at a cost of around $30, to see whether it would be cost effective to change any of them. They did, however, recommend vacuuming the dryer and refrigerator vents.

Alan Drake, who writes at the Oil Drum under the title AlanfromBigEasy, has, in the past referred to the success that Austin Energy has had in creating incentives to improve home energy use efficiencies. The program talks of rebates of up to $650 for installing recommended equipment types and weatherization. It has been very successful, the utility currently has a peak demand of 2,515 MW. It considers itself on target, however, to conserve some 700 MW of demand, by 2020, through improvements in energy efficiency of use.

However other programs, such as some of those carried out in Florida , have been either less successful, or the money saved has been spent inappropriately.
Florida Power & Light (FPL) hired eco-utility provider Green Mountain to market the Sunshine Energy Program to create demand for more than 1.2 million megawatt hours of renewable energy and over 450 kilowatts of new solar projects in Florida. Under the program, some 39,000 customers agreed to pay an extra $9.75 per month for renewable energy projects, but when a recent audit showed that three quarters of the $11.4 million collected from FPL customers since 2004 went to administrative, marketing and management expenses, customers started to complain. The problems escalated when FPL customers found out about an eight percent rate hike this summer, and another eight percent increase planned for January to cover costs associated with solar projects.

Sunshine Energy customers were promised renewable energy credits and solar development, and according to Green Mountain the costs for sales and marketing were $5.8 million, which resulted in 38,000 new customers in four years. So where did all that money go? Since 2004, Green Mountain made 56,000 hours of telemarketing calls, mailed 3.6 million pieces of direct mail, delivered 38 million enrollment forms on customer bills and sent 7.6 million bill inserts to market the program to FPL customers.


An Energy Audit is not inexpensive, but in these times, particularly with older homes, it can easily pay for itself, over time, in lower energy bills.

5 comments:

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