Green Building

HVAC Design Requirements in the International Building Codes

Prime:  prime Subtitle:  A look at what the codes actually require for load calculations and duct design Images: 

Building codes, especially those related to energy efficiency, have improved a lot over the years. With building enclosures, this has made a big difference. We now have more insulation, less thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel. , and tested air barriers. On the mechanical side, the improvements are significant — reduced duct leakage and mechanical ventilation in airtight homes — but there's still a gap between some code requirements and what's being installed.

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Converting Heating and Cooling Loads to Air Flow Needs

Prime:  prime Subtitle:  Here’s how Manual J software takes your inputs and gives you both the BTU/hour and cfm needed for each room Images: 

When you embark on the project of educating yourself about building science, one of the first things you encounter is the concept of heating and cooling loads. Every building has them. (Yes, even Passive House projects.) That's why we do heating and cooling load calculations. We enter all the details of the building, set the design conditions, and get the heating and cooling loads for each room in the building.

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Wingnut Real-World Testing of Basement Waterproofing

Subtitle:  UGL Drylok Extreme, Koster NB1 Grey, Xypex Concentrate: Do these interior waterproofing systems really work? Images: 

Back in May 2017 I wrote a blog about negative side waterproofing (NSW). But I was still feeling troubled. The standardized test for NSW from the U.S. Army Corps of Engineers (“Standard Test Method for Water Permeability of Concrete”) is frankly really complicated; the schematic seems impossible to decipher (see the Image #1 at the right). Instead of using this test, could we do a real-world, Wingnut-style test for negative-side waterproofing?

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Is a Ventless Fireplace More Efficient Than a Condensing Furnace?

Prime:  prime Subtitle:  An energy conversion conundrum for building science geeks Images: 

One of the primary benefits of a ventless gas fireplace is that you don't lose any heat up the flue. That's because there isn't a flue, of course. (The potential problems with indoor air quality, however, outweigh any benefits, so don't run out and buy one just yet. Or ever.) That ought to make it a winner for heating efficiency in comparison to any vented heating appliance, such as furnace or boiler. Even the highest efficiency condensing furnaces still lose some heat in the exhaust gases that go up the flue.

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Advice for Getting the Most Out of Your Insulation Contract

Prime:  prime Subtitle:  Hint: The same amount of insulation doesn’t always give you the same R-value Images: 

I love insulation. It's a wonderful thing because it saves energy. It makes buildings more comfortable. And it's pretty inexpensive considering how long it lasts (or should last). I get asked a lot for my opinion on the best insulation to put in a building and my answer is straightforward: A well-installed insulation is the best. I like fiberglass. I like cellulose. I like spray foam. I like mineral wool. I like blown, sprayed, batt, and rigid insulation.

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Is R-8 Duct Insulation Enough?

Prime:  prime Subtitle:  Code requirements are always a compromise between what’s best and what’s practical Images: 

If you know a little building science, you've no doubt seen a lot of problems that occur with air distribution systems. Ducts just don't get anywhere near the attention they deserve in most homes.

I've written about ducts quite a bit here and have shown problems resulting from poor design and installation. We all know how stupid some of those problems are. So today I'm going to talk about a problem that doesn't get nearly enough attention: duct insulation — even when the design and installation are perfect.

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Kingspan Kooltherm Phenolic Foam Rigid Insulation

Subtitle:  A deep-energy-retrofit project uses Kooltherm as part of a high-performance attic insulation system Images: 

Improving the thermal performance of an existing attic is often challenging: workers are faced with narrow cavities, low clearances, and claddingMaterials used on the roof and walls to enclose a house, providing protection against weather. systems that make it hard to achieve desired R-values while still maintaining the necessary drying potential of the assembly.

The house at 81 Chapin Street in Brattleboro, Vermont, is no exception. It’s a 100-year-old wood-framed two-story home that Alex Beck and Candace Pearson are determined to comprehensively retrofit to high performance.

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Adjusting Bath Fan Use in Winter

Prime:  prime Subtitle:  Do you really need to run it when you shower? Images: 

You may have heard or read somewhere that you should run your bathroom exhaust fan whenever you take a shower and then let it run for a while after you're done with the shower. Showers increase the humidity in the bathroom. Sometimes it gets high enough to cause condensation to appear on the mirror and other surfaces in the bathroom. And that can result in mold growth.

So you should always run your bath fan when you shower. Or so they say.

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Ventilating a Home in Cold Weather

Prime:  prime Subtitle:  You need fresh air, but bringing in cold outdoor air can cause problems Images: 

When I woke up Saturday morning, the temperature outdoors was -40 degrees. The wind chill was -100 degrees! It was just unbelievably, impossibly, inhumanly cold outside. Fortunately, that was on a mountaintop in New Hampshire and not where I was. I happened to have woken up on a mountaintop in North Carolina, where the temperature was a much warmer -3°F.

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