Wednesday, January 10, 2018

Ventilating a Home in Cold Weather

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You need fresh air, but bringing in cold outdoor air can cause problems
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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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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/ventilating-home-cold-weather

Thursday, December 21, 2017

Night Surveys: The Lights Are On, But Nobody is Home

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How Yale University's energy manager uses after-hours walk-throughs to save energy
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Julie Paquette has been Director of Energy Management at Yale University for about 6 years. That means the buck stops at Julie’s desk for the energy consumption of over 400 buildings on campus. Yale has a pretty sophisticated approach to energy, including the Yale Facilities Energy Explorer, an energy dashboard system that shows energy consumption and details for every one of those 400 Yale buildings.

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from Building Science http://www.greenbuildingadvisor.com/blogs/dept/building-science/night-surveys-lights-are-nobody-home

Wednesday, December 20, 2017

The Buy-in Problem

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From code compliance to Passive House certification, getting good work from contractors is hard
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Last week I read a nice little article by Steve Baczek about getting buy-in from the various stakeholders involved with building a home. He's an architect who works closely with the people who build the homes he designs. He's also a former U.S. Marine who understands the importance of what he calls "a ladder of leadership and responsibility."

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/buy-problem

Wednesday, December 13, 2017

Exterior Insulation on 2x4 Walls Versus 2x6 Walls With Cavity Insulation Only

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A look at some modeling results may help you decide
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If you live in the world of 2x4 walls, as I do, you may have wondered about the savings you'd get by going to a more robust wall assembly. The typical house in southern climes has 2x4 walls with R-13 insulation in the cavities. The two ways to beef that up would be to add continuous exterior insulation or to go to a thicker wall. But which saves more energy? And how do they compare to the plain old 2x4 wall?

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/exterior-insulation-2x4-walls-versus-2x6-walls-cavity-insulation-only

Wednesday, December 6, 2017

How Does a Heat Pump Get Heat From Cold Air?

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The physics of heat pumps isn’t really that difficult to understand
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Cold weather is coming back to Atlanta this week, so let’s talk about heat. An increasingly popular way to heat buildings these days is with heat pumps, even in cold climates. But how do they work?

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/how-does-heat-pump-get-heat-cold-air

Thursday, November 30, 2017

Extending the Reach of a Moisture Meter

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Simple ways to measure moisture content deeper into building assemblies
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Typical pins on moisture meters are ½ inch long, meaning you can only determine moisture content by weight near the surface of building assemblies and materials (including wood, gypsum wallboard, and concrete). But I often find myself needing to assess moisture content of first condensing surfaces in walls and ceilings or well below the surface of basement slabs.

This article looks at ways to extend the reach of a moisture meter. (For introductory information on moisture meters, see Tools of the Trade: Moisture Meters.)

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from Building Science http://www.greenbuildingadvisor.com/blogs/dept/building-science/extending-reach-moisture-meter

Wednesday, November 29, 2017

Two Rules for Humidity

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To prevent moisture damage from humid air, just do these two things
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Because I've written so much about moisture in buildings, I get a lot of questions on the topic. Some are about walls. Some are about the attic. Some are about windows. Some are about the crawl space (which generates the most questions on this topic).

The key to answering a lot of those questions boils down to an understanding of how water vapor interacts with materials. Once you know that, it's easy to see the two rules for preventing damage from humidity.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/two-rules-humidity