Building Science

Using David White’s Global Warming Calculator

Posted on December 7, 2016 by ab3

Everyone knows about the impact of burning fossil fuels on global warming. Maybe not everyone believes it, but scientists first started focusing attention on increasing carbon dioxide levels way back in 1827. The impact of insulation on global warming, however, is relatively new.

Revisiting the Debate Over Global Warming and Insulation

Posted on November 23, 2016 by ab3

At the North American Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. Conference in Philadelphia in September, I gave a presentation on the global warming impact of insulation, an issue I've discussed a few times since Alex Wilson wrote his paper on the topic back in 2010. In my presentation, I covered two different aspects of the issue: (i) the problem with Wilson's payback calculations and (ii) using David White's global warming impact calculator to make more informed decisions.

SEE STACK is a Cool Stack-Effect Tool

Posted on November 17, 2016 by Peterbilt

In 2003, as part of their presentation (“Ventilation Myths and Misconceptions”) at the Affordable Comfort conference, Collin Olson and Paul Francisco debuted a software tool they developed called SEE STACK. (If you want to experiment with the software, click here to download the executable file and training manual).

Do Humidifiers Create IAQ Problems?

Posted on November 16, 2016 by ab3

It's that time of year when heating systems start coming out of their summer hibernation. (Except maybe in Vermont. Michael Blasnik's Nest data showed that Vermonters are about the last to start heating their homes in the fall.) Then everyone starts looking for their lotion and lip balm. Gaps appear in hardwood flooring as it dries out. Buildings begin to creak and pop. And then the humidifiers come out.

Yes, humidifiers can help with low indoor humidity. But what effect might they have on indoor air quality?

Using Rooftop Solar to Meet the Energy Code

Posted on November 9, 2016 by ab3

Supply and demand are two different things. When you think of an energy code, say the International Energy Conservation Code (IECC International Energy Conservation Code.), you probably think of demand, not supply. Conserving energy, after all, means reducing demand. It's related to supply only indirectly.

As a result, you might expect an energy conservation code to have requirements that affect only the demand side of the equation. With the 2015 IECC, however, that's not true anymore.

High Humidity in Spray Foam Attics

Posted on October 26, 2016 by ab3

I recently investigated an attic with spray foam insulation where we observed an interesting humidity pattern. We placed data loggers near the ridge and floor of the attic as well as in the living space and outdoors.

The graph at below shows dew point data for the four locations. The really interesting part is the big difference in dew point between the highest and lowest points in the attic, shown by the red and green curves in the graph.

Building Science Puzzles: The Jigsaw Approach

Posted on October 20, 2016 by Peterbilt

Just about every week, I get a call or an email that turns into a building science puzzle. While the problems are varied, how you solve them doesn’t change.

First, you understand how heat and moisture move through building assemblies. Second, you follow the advice of your spouse.

My wife of 27 years is a real master at jigsaw puzzles, and she would laugh to learn that I think of myself as a puzzle master of any sort, since I am useless at the jigsaw ones. But she completely agrees that I should use her method of solving jigsaw puzzles in my work on building science problems.

Buildings Don’t Need to Breathe

Posted on October 19, 2016 by ab3

Breathe. It's a good thing. We need to breathe to live. Breathing consciously relaxes us. “Breathe” is also the name of a great song by Pink Floyd from the Dark Side of the Moon album.

Breathe, breathe in the air
Don't be afraid to care
Leave but don't leave me
Look around and choose your own ground.

Breathing is required of many life forms. But when it comes to buildings, all this talk of breathing is just confusing.

Does Cheaper Solar Mean We Can Forget Efficiency?

Posted on October 12, 2016 by ab3

Solar energy has sex appeal. If you want to show the world you're doing something to reduce pollution, you put photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. (PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.) panels on your roof to generate clean electricity. Even better, you drive a plug-in hybrid or an all-electric car and charge your car's batteries with your clean solar electricity.

The good news for solar enthusiasts is the cost of installing a solar electric system on your home just keeps falling and falling. Let's take a look at some data and then ask if it’s time to abandon energy efficiency.

Installing an Exhaust Fan During a Bathroom Remodel

Posted on September 28, 2016 by ab3

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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