Energy Vanguard Blog

Air Conditioner Sizing Rules of Thumb Must Die

Posted by Allison Bailes on Fri, Aug 26, 2016

We design a lot of heating and air conditioning systems at Energy Vanguard. Alexander Bell, who goes by Andy, is our design wizard, and I've been getting involved with the process again lately. When I talk to potential clients, a lot of them tell me their contractor wants to size their air conditioner using a rule of thumb. The rule is usually something like this: Install one ton of air conditioning capacity for every 500 (or 600) square feet of conditioned floor area. How far off are they? Let's take a look.

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Tags: comfort, heating & cooling

Installing an Exhaust Fan During a Bathroom Remodel

Posted by Allison Bailes on Tue, Aug 23, 2016

Remember my bathroom remodeling project? I took the liberty of gutting our outdated, decaying bathroom while my wife was out of town in April. I found some interesting air leakage pathways when I opened the walls. I fixed that. I found termite damage. I fixed that. Our 1970 condo didn't have an exhaust fan in this bathroom because, hey, who needs a bath fan when you have a window! I fixed that. Here's how.

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Tags: moisture problems, ventilation

3 Reasons to Remove Attic Floor Insulation in a Spray Foam Attic

Posted by Allison Bailes on Tue, Aug 9, 2016

I get asked a lot of questions about spray foam. Do I need an ignition barrier? Should I use open cell or closed cell spray foam? Will open cell spray foam really rot my roof? But the question I get more than any other on this topic is about whether or not the insulation on the attic floor should be removed when insulating the roof deck in an existing home. As you can tell from the title of this article, my answer is to remove it. Here are my three reasons, in increasing order of importance.

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Tags: insulation, air leakage, indoor air quality

Can You Ventilate a Home with Attic Air?

Posted by Allison Bailes on Fri, Aug 5, 2016

I've seen some crazy things done to homes. It's usually someone's attempt to make things better. Sometimes that someone is a homeowner or other occupant. Sometimes it's a contractor. But it always seems to be a solution to a problem that creates other problems. It's just like they say: Our biggest problem is solutions. So what's the problem with this method of ventilating a home?

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Tags: attic, indoor air quality, ventilation, heating & cooling

Only One Person Can Fix the Passive House Rift

Posted by Allison Bailes on Fri, Jul 29, 2016

In the beginning, there was passivhaus. That was way back in the 1990s. Then the Passive House Institute US, having been thrown out of the party for blasphemy, said, no, passive house started in North America in the 1970s and '80s. But wait, others said, a polar exploration ship from the 19th century was truly the beginning of passive house. And Dr. Joe Lstiburek, as you may recall, said it was the Eskimoes who started it.

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Tags: fun, Passive House

Why a New Standard for Passive House?

Posted by Allison Bailes on Wed, Jul 27, 2016

There's this thing called passive house. It's a terrible name. Almost everyone agrees on that. Look at how its adherents are driven to a frenzy and you'll see that the name doesn't really fit. The houses themselves aren't passive either, but let's leave that aside for now. Let's talk about numbers and objectives. The North American Passive House program of PHIUS grew out of the German Passivhaus program, which has one set of targets for the whole world. Now PHIUS has adapted the German standard to suit North America. It's an important change. And the frenzy of the adherents has been fun to watch!

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Tags: environment & sustainability, Passive House

3 Cool Products I Saw at the Passive House Conference in NYC

Posted by Allison Bailes on Fri, Jul 22, 2016

Last month I attended the conference of the North American Passive House Network in New York City. They had a really nice trade show, and I got to spend some time talking to the vendors. It's always nice to see what's going at these events because I'm starting to come around to Joe Lstiburek's way of thinking. At the 2013 Building Science Summer Camp, he said, "Passive House is the only place where real innovation is happening."

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Tags: conferences, ventilation

The 2018 Building Code Makes a Change in Ventilation

Posted by Allison Bailes on Thu, Jul 21, 2016

Ah, ventilation. One of the easier topics in building science. Everyone agrees: We need airtight houses. Airtight houses need mechanical ventilation. Build tight. Ventilate right. No problem! We're all on board. There's nothing to disagree about. Right?

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Tags: indoor air quality, ventilation

How I Achieved a 21% Increase in Airtightness

Posted by Allison Bailes on Mon, Jul 18, 2016

I've got a record of 14 blower door tests on my condo. Many of them were during home energy rater classes, as we'd bring them here for the confirmed rating they needed to complete. The early ones were horrible! But I had a good reason. Our laundry room ceiling was half gone because of a water leak. (Thanks, upstairs neighbors!) After that we had a bunch that were still bad. Now we've had another big jump in airtightness. Wanna see the numbers?

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Tags: fun, air leakage

How Much Insulation Do You Need in a Passive House?

Posted by Allison Bailes on Fri, Jul 15, 2016

Passive house has a reputation for requiring ungodly amounts of insulation. It grew out of the superinsulation movement after all. If you're familiar with any passive house projects, you may be thinking about double-stud walls that are a foot thick or regular walls with 6 to 12 inches of rigid insulation on the outside. But how much insulation can you use and still meet the requirements of the Passive House Institute US (PHIUS)?

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Tags: environment & sustainability, heating & cooling