Residential Energy Compliance State Regulations

[michael]

That's good! And I'm feeling the pressure! One correction, however, is that in Dec-Feb, the average low is 40 while the average high is 52, so the daily average temperature difference might be more like 45-70 instead of 30-70. When it does reach 30 at night, it's much warmer by mid-day. So, your figures could be modified a bit to around 25k BTU/d. That would require our heater to burn $1.50 in diesel to make up the lost heat. If that were the case, on average, for a third of the year, we can expect to pay something less than $200 for the benefit of fresh air. When I have a heat pump installed that cost should be rather less, say $70-80 per year. I wonder how that compares to the 5 or 10 year amortized cost of an HRV plus operating costs. Honestly, I really like the idea of HRVs, certainly far more than blowing lots of dearly heated air out the side of the house, but I just want to check out the trade off. I like your persuasive arguments. mm

[Exeric]

Hi Michael,
I can feel you getting in the middle of a tug of war so I"ll try not to add to that. Since one has to have a regular bathroom fan anyway you really aren't wasting money by getting one with a constant low CFM rate in addition to the high "on" cfm mode. Just think ahead while you are still in the planning stage for where and how you would install an HVR if you decide to install one later and make construction provisions for it.

Let your own experience living in the house be your guide whether to go for the expense of an HRV at a later date. That would be the smart way to attack the problem, (if there is one).

[Exeric]

Michael, one more thing to think about. It sounded like you weren't using forced air for the temperature conditioning system of your house. Perhaps I'm wrong. But if you aren't that means if you have the bedroom doors closed at night for a guest or to conserve temperature in the bedrooms, then air in the bedrooms will no longer circulate from a bathroom fan. It doesn't sound like you'll have the temperature problem but you will have the air circulation problem if the bedroom doors are closed at night.

The house I'm renovating doesn't have forced air either and will just use a bathroom fan. To get around the stagnant bedroom air at night I'm going to put a return air duct from the bathroom floor to the bedroom floor through floor registers. I also plan on putting another return air duct high up on the walls in each bedroom that separates the bedrooms from the living room. That way I'm creating a path for warm air near the ceiling in the living room to move into the bedrooms at night. The colder air near the floor in the bedrooms will be sucked into the bathroom from the bathroom fan through the floor registers connecting the bathroom and bedrooms.

The plan is to not undercut the bathroom door as is usually done on the bathroom door to provide air circulation. Instead I'll just keep the bathroom door closed at night and then force the air circulation path through the bedrooms. Hopefully it will also let me turn down the heat at night and use the main living space for the heat reservoir helping to heat the bedrooms at night (or during the day). I hope it works.