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In my experience, air sealing has been a very rewarding investment in my rented apartment. It is a renovated barn, and had all kinds of gaps around timbers where they joined other timbers or butted up against sheetrock.

The first winter I used over 400 gallons of propane, which motivated me to spend a couple of days sealing gaps with spray foam, caulk, backer rod, and even some wooden blocks to cover the largest holes. I also dropped the thermostat 5 degrees the next winter, and saw my fuel usage drop significantly. I did a bit more sealing the next year, and since then I've burned about 200 gallons/year.

Admittedly,the apartment below mine is heated, so I think lowering my thermostat has an even larger affect than in a stand-alone unit. Not only is the heat loss from my apartment to the outdoors decreased, but the thermal flux across my floor into my space from the apartment below increases as my air temperature drops.

An added benefit is that the cigarette smoke odors from neighbors have gone down from the air sealing as well--since the entire building structure is connected in strange and leaky ways, I have tried to seal all joints even in interior walls.


Great point about the reduction in smoke and odors caused by air transfer! Thanks, Abe.

Harold Orr

An interesting project but is "stealing" heat from your neighbor cricket? What does 650 CFM50 represent in air changes per hour at 50pascals? (ACH50) After you had done all the air sealing where were the major leaks remaining? Do you now need an A-A heat exchanger? How much further tightening would be needed to make an A-A heat exchanger cost effective? You have reduced the leakage but you have also increased indoor pollution. Is this going to be a health problem?


Harold, it's GREAT to "see" you! In the words of The Carpenters, We've Only Just Begun. 650 CFM50 in this house is a bit over 2 ACH50. We have mechanical ventilation in the exhaust fan for the composting toilet, and one of my investigations will be whether I can run that necessary exhaust through a heat recovery ventilator without detectable air quality issues. I hope this week to remove the second of two indoor air quality problems - a gas range. The first was the oil boiler. Stay tuned!


Oh - the bulk of the remaining leakage I believe from the zonal pressure diagnostic work is in the basement at the sill and rim joist area. Although we have lots of intentional holes - a direct vent gas heater that will be going, a clothes dryer, the oil boiler inlet and vent.


Marc, I'm glad to hear you talking about heat recovery from composting toilet exhaust--it's something that's been nagging at me, too. If you try hooking it to an air-to-air exchanger, I'd love to hear how it works. I imagine the filter on the exchanger filling up pretty quickly, since the exhaust can be damp and dusty. Have you considered building your own exchanger out of coaxial ducts, with the air intake running inside of the exhaust pipe? I don't know how efficient that would be, but it would require no filtration of the exhaust, just perhaps a cleaning of the pipe every decade or so.

P.S. @Harold: I did consider the ethics of keeping my apartment cooler than my downstairs neighbor's, but decided that I wasn't going to burn lots of extra propane heating my space beyond my needs, just to keep his ceiling slightly warmer. I wouldn't do it if it were zero-sum--if every gallon I saved cost him a gallon extra--but since I share four walls and a cathedral ceiling with the outdoors and only one floor/ceiling with my neighbor, I feel fine about keeping my place at the temperature I prefer. But yes, it is true that I am profiting slightly at another person's expense.

Heating and Plumbing

Never got to work with such situation, this looks little bit weird as the finishing doesn't looks that good to me but still as it works would love to try out someday.

efficient gas furnace

I have never heard about air sealing. By this post i think air sealing is necessary for our homes. It reduces smoke caused by air transfer. I would like to try this one day. Thanks for sharing.

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