Q&A: A Forum for Green Building Experts and Beginners

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!


2 Answers

Solar thermal doesn't seem dead when I read about this:

I keep seeing it mentioned here in blog posts, etc, that solar thermal is dead. Just use PV and electric water heat. Okay, makes enough sense. But then I came across Solaris when it was mentioned in one of the comments of a blog post (http://www.solar-hot-water.ca/).

In Green products and materials | Asked By jonathan nagar | Mar 6 14
1 Answer

Rigid foam sandwiched in wood subfloor?

Hi,

I'm re-doing my living room floor.

When I strip it down to the T&G subfloor, I will have about 1" to make up, since it will be lower than the kitchen floor it butts up against.

Below is an unfinished. basement.

Originally I was going to do OSB as a base with a layer of thinner plywood to get up to the proper height. But I have seen a lot of people doing rigid foam in their basement floors - Foam, then ply or OSB, with flooring on top.

In General questions | Asked By Sean Cunningham | Mar 7 14
1 Answer

Woo-woo alert!

Took a wander through the Building Energy trade-show floor yesterday,
and found a booth handing out flyers about a distinctly sketchy-
sounding fix for rising damp in masonry buildings called "Aquapol".
Aquapol-usa.com for the english website; claimed to have originated
in Europe with thousands of successful deployments. But when they
start talking about rather long-distance non-contact effects on
moisture not to mention various vagueness about "free energy", my
skepticism meter starts jumping. Can anybody comment on this stuff?

In Green products and materials | Asked By Hobbit _ | Mar 6 14
3 Answers

Spray foam - can I spray a second layer of foam over the first layer? If so, any preparation required?

Home owner wants twice the foam thickness - currently has 0.5 inches on underside of flooring, & wants to double this.

In Energy efficiency and durability | Asked By Carol Monteagudo | Mar 6 14
7 Answers

Heat pump COP and preheating

Has anyone ever seen an analysis that indicates the benefit of having an air source heatpump run more before the nightly temperature drop in order to obtain a higher COP than later in the night?

A similar pre-charge could be done for cooling before the outside temp rose a lot.

In the past with leaky poorly insulated houses I don't think this made much sense, but now with some very tight and well insulated houses I belive it would be beneficial.

The main trick is to mine weather report data and control the thermostat based on COP curve, energy loss rate, and heat schedule.

In Energy efficiency and durability | Asked By Ed Miska | Mar 5 14
1 Answer

Opinions on the VENTS-US single room ductless ERV?

VENTS-US single room ductless ERV units

Any familiarity or opinion about the VENTS-US single room ERV called TwinFresh Comfo. Are the performance claims any good? For apartments, lofts, cottages and small homes? Can they be used in same building where exhaust-only ventilation is in the bath and kitchen?

http://www.ventilation-system.com/cat/618/

Apparently Home Depot is where they sell:

http://www.homedepot.com/p/VENTS-32-CFM-Power-5-in-Single-Room-Energy-Re...

In General questions | Asked By fitch plate | Mar 6 14
1 Answer

Can a furnace be cleaned and reused after a house fire? Or should it be replaced?

I am working with a homeowner on the design of an addition to a house. Prior to starting construction on the addition, the existing house had a fire which was contained to the laundry room. Smoke damage, however, is throughout the existing house. The mechanical room is accessed through the laundry room. The furnace was running when the fire started, and then turned off. There is evidence of smoke in the furnace (in the filter and at the connection to the AC). I have one contractor suggesting that the furnace can be cleaned, serviced and remain.

In Mechanicals | Asked By Corri Sandwick | Mar 6 14
1 Answer

Concerning moisture inside open cavity stick-built walls

My project is in DE near the beach - a high moisture area. I have a slab on grade "cottage". The walls are 2x4's on 2'0 centers vertically with 2x4's also on 2'0 centers horizontally to the outside of the vertical studs - covered by painted T111. The "lid" is conventional trusses, vented, with foil faced rigid foam on the underside of the bottom truss chord. It was supposed to be a garage but it has morphed into a secondary living space for overflow guests, parties, etc and I want to use an air conditioner in there.

In General questions | Asked By Greg Burnshaw | Mar 6 14
2 Answers

Water Heater selection help - Gas or Electric, Tank, Hybrid, Tankless?

I am in the process of needing to update my hot water tank (Currently a 40 Gallon gas water heater). I live in Michigan and have been trying to figure out what makes the most sense (Environmentally and economically). I am considering adding solar panels to my roof next year, so I was thinking of changing to electric but I have not found much information about electric tankless systems being used in Michigan other than I would need a large unit to provide for the entire house. I have 3 full sized bathrooms, a dishwasher a kitchen sink, laundry room sink and a wet bar sink.

In Mechanicals | Asked By Roger Ratkowski | Mar 6 14
1 Answer

Insulation / moisture

Hello, I am buying a concrete block house. I will have to do some extensive renovations. I have brought a structural eng. to the site . He has told me that the exterior concrete block walls and foundation are fine, as well as the attic system. The rehab needs to be done inside. Due to previous water leaks inside the interior footings,girt beams and floor joists have to go and be completely redone.

In Energy efficiency and durability | Asked By john afanasiw | Mar 6 14
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!