Energy Audit and Energy Saving Recommendations
Today's Power Trip - Energy audit with cadet heaters and a low minimum ventilation level
Always hate to head out on a home audit when it’s raining. Here in Western Oregon, it happens a lot. Supposed to be possibility of thunderstorms this evening, but that’s OK, because the thunderstorms around here are pretty tame compared to other parts of the country.
The home today is a kind of kit home. The builder offers a certain set of basic plans that they build on your land. They build the same few simple plans over and over and have the profit line down to the bare nickel. Making changes to the plan is a no no. Take the home as drawn or forget it. Don’t get me wrong, the builder does a lot of things right and the home, when finished, is worth the nickel. This home was built in 2004 and has 2100 square feet on two floors. The homeowners are interested in saving power and lowering their electrical usage so have asked for an energy audit.
Let’s take a closer look, I found a few things about this home that I don’t run into very often when I’m doing an energy audit.
First of all, it is a little unusual to find this size of home that is heated by electric wall space heaters. It’s one of those things this builder won’t let you change. The builder can advertise a very attractive cost per square foot and less expensive space heaters is one reason why. Homes of this size usually will have a central, whole house, heating system.
In this house, each room has a heater with a thermostat on the wall above it. I always wondered about having the thermostat on the wall right above the heater. The warm air from the heater rises to the thermostat and turns off the heater before the other side of the room is warm. Something does not seem right about that.
The second thing that makes this house a bit unusual is the attic fan. The attic is ventilated by an attic exhaust fan mounted through the roof near the roof peak. The exhaust fan has a timer switch mounted on the wall in the upstairs hallway. Now, it was about 53 degrees outside and the attic temperature was about the same – guess what, the attic fanwas running. According to the timer switch, the fan was set to operate three times a day for a total of 14.5 hours.
The timer switch itself was set to 9 AM when it was actually 2:30 in the afternoon. Bottom line is – the attic fan is running up the electric bill when it doesn’t need to be. Oh, couple more items on the attic exhaust fan. The fan also had a temperature switch located on the fan itself. The temperature was set to activate fan at 125 degrees which was not functioning at all.
Also, the homeowner said the builder told them that the fan had to run “a lot” or the warranty on the house would be voided. Now, here is a builder really worried about mold in the attic and it appears he uses an attic fan as insurance.
The third item I found unusual about this house is the second timer switch I located - and this one is connected to the water heater. The homeowner indicated they were told by the builder that putting a timer on the water heater curcuit was something they did on all their homes. As far as I know, the builder didn’t say why. The water heater is a A.O. Smith, 50 gallon model with water temperature set to 120 degrees. The water heater is located in the downstairs entry closet with the timer mounted on the wall above it.
The timer is set to turn off at 10 PM and come back on at 4 AM. However, the timer itself is set at 8 AM when it is actually 2:30 in the afternoon. Looks like timer switches do not keep time very well. The homeowner did comment that the hot water did not seem as hot at times. By golly, I think we found the answer to that problem.
To tell the truth, I’m not sure whether shutting off the water heater at night is a cost saving measure or not. If it is, maybe we should be shutting the water heater off while we are at work also. We are going to have to talk about this more later.
At this time in the audit, I get around to asking the homeowner for an electric bill. On this bill, like most bills, there is a bar graph that compares the current months electrical usage with the previous12 months. This bar graph is very important in evaluating a homes electrical usage.
For this home, I notice right away that the ‘every month’ usage is high (the base load) and the spikes in usage for summer air conditioning and winter heating are not that much higher than the everyday stuff. This tells me there is too much juice being used for everyday base load stuff and that the house is probably well insulated with a good air barrier because the heating and cooling spikes are small.
Minimum Ventilation level
I checked the homes air tightness level with a blower door test. The test resulted in a house air leakage figure of 840 cfm (cubic feet per minute) at 50 pascals depressurization. People, the house is tight. I would not want to do any air sealing work on this home because I would risk causing the air in the house to become stale and the house to feel stuffy.
The minimum ventilation level (MVL) for this home, as determined by people smarter than me, is closer to a number equal to the square footage of the home. Around 2000 cfm. ( I will take the opportunity to go over the recommended MVL and how it is calculated in future Insider reports.)
The homeowners have some money to spend on upgrades to their home that will save power and save money.
Here are my energy conservation recommendations.
1. Become relentless at evaluating their power bill. Check the bar graph and the killowatt hours used every month. Look for improvement.
2. Replace the attic exhaust fan with a solar powered fan. The warmer the sun the warmer the attic. The warmer the sun, the more your attic fan runs. Cost of installation $250 to $700. Cost of operation, zero.
3. Disconnect water heater timer. Keep a close eye on usage.
4. Install new dishwasher. Home came with a very basic dishwasher, no energy star here. Homeowner says they run the dishwasher through two cycles in order to get the dishes clean. (Might wash the dishes better before putting in dishwasher, only run full loads.)
5. Install compact flourescent light bulbs. The homeowners were surprised to find they had 57 light bulbs in the house. Three were CFL’s. Cost for replacement bulbs about $150.00. (Most of us do the replacement over time)
6. Install a whole house heating system. Recommend electric furnace with heat pump. Cost of installation about $7,000.
Thank you for stopping by Detect Energy, hope you join me again real soon for another energy audit, but I won’t leave the light on for you…