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19 Answers

HERS ratings & kBtu/sf/yr

Is there a direct relationship between HERS ratings and actual energy use, such as kBtus/sf/yr? Energy Star is gaining traction and making incrememtal improvements to their standards. Stretch Codes in Massachussetts pretty much make Energy Star the default route to comply. So the HERS rating is gaining traction for consumers. Its based on a scale with "0" being a Zero Net Energy Home, and 100 being a code-based home from 2003 or some such year. But I wonder how the HERS rating is related to energy use per square foot per year.

In Energy efficiency and durability | Asked By Chris Vlcek | Jan 29 10
3 Answers

Any ideas on the best way to provide a thermal break when using steel studs?

The structure is in Charlotte, NC. The wall assembly is curently drawn as 4" metal studs with Icynene insulation, 7/16" OSB fastened directly to the studs, 2 layers of felt and siding.

In Energy efficiency and durability | Asked By Doug Mcspadden | Feb 7 10
4 Answers

Attic Air Sealing


I was wondering if there was a way to easily air seal an entire attic?

The attic is vented and unfinished with fiberglass batt insulation. The insulation and air gaps are located beneath a wood plank floor that has been nailed down. If I wanted to air seal the traditional way I would have to pull up all of the floor boards, the insulation, and then find and seal all of the gaps. Is there an easier way to to air seal over the gaps, existing insulation and wood floor?

In General questions | Asked By Graham Mink | Feb 5 10
17 Answers

Sizing exhaust only ventilation?

I am roughing in plumbing and electric and need to add ducts if we choose to use an HRV which is what I had originally planned. The house we are building has radiant floor heat in the basement and an outside air supplied sealed fireplace on the first floor so no ducts yet. Some other costs have exceeded estimates and I am thinking of using an exhaust only system to ventilate the house (Northern Michigan approx. 8000 HDD, R-40 walls, R-60 roof, hopefully fairly tight, about 2400 sf).

In Mechanicals | Asked By Donald Lintner | Feb 1 10
3 Answers

Discussion topic : Why we should consider simplicity during the design phase.

I came across a posting from Robert Bean's Healthy Heating site. I took a HRAI course that he taught on Radiant Hydronic when I started thinking about how I'd heat my house. The points he makes are somewhat aimed at hydronics designers but can apply to the whole house as a system too I believe.

In Energy efficiency and durability | Asked By Andrew henry | Feb 5 10
2 Answers

Dense-packed insulation

I've worked with blown cellulose a few times, in attics and such. Each time I rented a blower from a big-box store. However there seems to be no provision for dense packing with these machines. Where do you find /rent dense pack machines and find good usage directions? Thanks.

In Green building techniques | Asked By Scott Mangold | Nov 25 09
3 Answers

To those who attended the 2009 Passive House conference.....

The Passive House Institute-US had made available for viewing and downloading the presentations made at the conference. I'm glad they did this-there was a lot of great information and seeing it again does make one re-energized!



In PassivHaus | Asked By Derek Vander Hoop | Feb 4 10
6 Answers

Tradeoffs of passive heating and cooling strategies

Has there been any conclusive research done on how to negotiate the tradeoffs of passive heating and cooling strategies based on climate and location? Most specifically, should things such as light-colored roofs and minimal east- and west-facing windows be done in all climates in the U.S. or does it depend on whether or not your climate is predominantly heating or cooling. I have heard both positions from different building science experts.
If anyone has numbers to back up their opinion, that would be greatly appreciated!

In Energy efficiency and durability | Asked By Karen Leu | Feb 2 10
5 Answers

I have a 4-year-old home I built myself.

I used blown-in fiberglass up top. I went up the the attic to look lately and found that it has settled about 4 inches. I would like to use some cellulose to blow in on top of the old insulation.
Yes or no? Please help.
Fiberglass or cellulose?

In General questions | Asked By Ryan O'Dell | Feb 1 10
2 Answers

Does a hydronic air handler provide greater efficiency than a highly efficient natural gas furnace?

I have not been able to find any information showing measured efficiencies of hydronic air handlers. For one, hydronic air handlers seem hard to come by (unless I'm looking in all the wrong places). The only reputable manufactures to offer them to my understanding are LifeBreath and Lennox. Neither manufacturer provides any information regarding how the efficiency of a hydronic air handler compares to a natural gas furnace or any measure of efficiency at all.

In Energy efficiency and durability | Asked By Mike Maraghy | Feb 2 10
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