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29 Answers

Automatic control for passive solar overheating in winter?

Hi, I’m designing a passive solar house and attempting to gaining the most energy from the sun, but the more energy you try capture, the more likely overheating becomes a risk on those warmer, sunnier winter days. I was thinking it would be simple enough to have an ERV with a bypass that can exchange overheated indoor air (say 80°F) with the cooler outdoor winter air (say it’s 60°F) when the indoor temperature hits a upper limit setpoint (say 75°F) and the outdoor temperature is cooler.

Asked By Mike AbiEzzi | Oct 20 17
4 Answers

Closed cell spray foam/cellulose combination

To all,

Background: 1500 Sq Ft. single level home, Northern Minnesota Zone 7, almost 10,000 HDD.

I am getting ready to insulate my double studded walls. The wall cavity including 2 2x4 24"OC studs separated by a 1" gap for a total cavity of 8". The ceiling has 2' energy heel trusses with 24+" of blown in cellulose

The original plan was to insulate the whole wall in cellulose, and at R3.9/inch the goal was 31 with no thermal bridging. Inside the cavity there was going to be a smart membrane (Intello Plus)

Asked By Steve Lenertz | Oct 21 17
5 Answers

Drainage and/or waterproofing for stem walls

Hi all.

I am planning to dig a trench around a garage (stem walls with interior slab on grade) to install some EPS foam.

The soils are clay heavy.

Would it be worth:

1) Also adding drain pipe next to the footing with crush stone, geo-fabric and sand back fill thereafter? NOTE: the garage is an attached and is slightly uphill of the house, which itself does not have exterior drains. So my thought is that, at the least, this may help divert some water from the house which has a basement.

2) Also waterproofing the concrete.

Asked By Tyler Keniston | Oct 22 17
4 Answers

Can you safely close air intakes?

We added solar panels to our house this year and switched our boiler from propane to electric. We have been optimizing our system of radiant heat through the floor by utilizing programmable thermostats and utilizing the variable speeds of the pumps pushing the water through the floor. We noticed today that we have cold air intakes almost directly above the thermostats in two rooms. It feels like the A/C is on while the heat is on. A hand-held laser thermometer is showing the cold air intake at 48 degrees directly above the thermostat which is set at 65 degrees.

Asked By GaryJanL | Oct 22 17
1 Answer

Hot Spot Energy: anyone heard of them or used their products?

Tripped over a company (small?) I'd never heard of with neat energy recovery products called hotspotenergy. Anyone ever worked with them or their products? I'm particularly interested in the ac waste heat recovery devices.

Asked By Keith H | Oct 22 17
4 Answers

Vaulted ceiling, open attic

I have two vaulted ceilings that I am trying to work out how to insulate. I have read all the material here on insulating cathedrals. However these are essentially a variant on an unconditioned, vented flat attic. If the roof is 6/12, the ceiling is 3/12. Unfortunately while they are not a classic cathedral with only a stud's depth, they still have very little space between the ceiling joist and rafter, ruling out fluffy insulation. (The R-38 batts already brush the roof sheathing halfway down the slope) Dense pack, of course, I hear is a very bad idea due to moisture.

Asked By pshyvers | Oct 21 17
3 Answers

How to get Passive House educated?

Hi everyone,

Asked By DHTaylor | Oct 21 17
9 Answers

Foam first or last in cold enclosed porch floor?


I have seen this question answered many ways while searching online, so I thought I would pose it here. I know there is another thread on this topic, but it seemed worth posting again.

When insulating an enclosed porch that is not climate controlled, should the layering be: pink foam board affixed to the floor underside, fiberglass batts, plywood for vermin control?

Here's the application:

Asked By JonesyHome | Oct 12 17
5 Answers

Heat loss from floor drains to daylight

We are in Minnesota (Zone 6a). 2200 sq/ft single level, slab on grade.

This question has been in the back of my mind for quite some time and I can't find an explaination about heat loss from floor drains to daylight. I will heat our garage to about 45 degrees F, and have 2 floor drains that run to daylight. Seems to me that this will be not only a drain for water, but a drain for heat as well. Are there any stratagies for minimizing heat loss through the drain? We are not allowed by code to connect this to our septic system.

Asked By Scott K | Oct 21 17
3 Answers

Installing a one piece shower


My cousin and I are installing a one piece shower this weekend, in his guest house he is building on his property. Property is located in zone 3.

I told him I would do a little bit of research beforehand.

He is using an interior vapor retarder called intello plus. I am wondering if it is ok to install the shower directly over this or if there is any reason drywall should go up first?

Also, the manufacturer requires no cements bed under the shower. Would it be wise to lay a vapor barrier cutout underneath the shower or can we just install directly over the plywood subfloor?

Asked By MichaelBa | Oct 21 17
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