Category: Building Science

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Building Codes and Building Science are Beginning to Better Align

This post first appeared on the Green Building Advisor website.

I’ve heard Mike Guertin mention that every home built is a building science experiment.  It can take some time for problems in buildings to be known.  For instance, a bad detail on a window installation, like shown in this photo, could take more than 20 years to present as a problem.  If the problem is being repeated, building science might identify the issue and propose a change.  Eventually, the change may end up in the building codes, but this whole process is slow.

That being said, there are many building science principles that we have figured out, with several already added to the codes.  Some have been known about for decades but are still slow to be adopted.  Let’s discuss a few of each.

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Why Knowing Your Climate Zone is Important

Figure N1101.7 (R301.1) Climate Zones-2021 International Residential Code (IRC)

This climate zone map is published by the American Society of Heating and Air-Conditioning Engineers (ASHRAE) and is included in the International Residential Code, chapter 11, Energy Efficiency.  ASHRAE’s purpose is to create standards of how an engineer or HVAC professional calculates and designs heating, air conditioning and ventilations systems to match the insulation, air sealing, and moisture profile of a building.  When designing these often-complicated systems, where the structure is located becomes key, this is the reason the map was created.

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How Well Do You Know Building Science?

This post first appeared on the Green Building Advisor Website.

The International Builders Show took place from February 27th through the 29th, 2024 in Las Vegas, NV.  The past couple years, Huber Engineered Wood has held a building science trivia game in their booth.  The game is played using an app on a cell phone, questions are answered by contestants and their score is based both on how quickly the question is answered and whether the question was answered correctly.  The game is just for fun, though there are some bragging rights if you are able to beat the on-stage contestants.  This year, the on-stage players were Jake Bruton, Steven Baczek, Peter Yost, and Ben Bogie with Tate Hudson from Huber asking the questions.  (Jake has this year’s bragging rights.)

I thought it might be fun to have a version of building science trivia here on the Northern Built Blog.  Some of the questions being asked are from the game played in the Huber booth, others are questions that were asked during another building science trivia game played a recent BS and Beer-Northern Minnesota meeting.  The game is just for fun, you keep track of how many you get right.  The answers (along with a little more in-depth information about the answer) will follow the quiz.  Here we go.

  1. The climate zone map located in Chapter 11 (Energy Efficiency) of the 2021 International Residential Code Book contains how many different climate zones?
    1. 8
    2. 9
    3. 14
    4. 19

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Common Building Science Mistakes to Avoid

This blog post first appeared in two issues of Fine HomeBuilding Magazine: Issues 321 and 322.  Part of a series that included 17 short articles written by 7 different authors.  My first contribution appeared in the letters and reader feedback section of the February/March issue, titled “The biggest mistake of all?”  You can read that post here. 

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Construction Design-What Is and How to Achieve Acoustical Comfort

This post first appeared on the Green Building Advisor website.

How do you define comfort inside your home?  Thermal comfort is the big one, not being too hot or too cold.  Thermal comfort is one of the most important questions I ask during building investigations and energy audits.  Having the right indoor humidity is another, not too damp and not too dry, which can affect not only comfort, but also human health and the durability of the structure.  How about the visual aspect of comfort, it’s always nice to be in a room that “feels good” simply because of the way it was designed or how it is furnished.  This discussion on comfort though is going to be on sound, the noises you experience inside the home and how noise pollution can affect comfort.

My sound level meter.

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Windows-Water and Air Sealing

I’m going to make a statement that not everyone will agree with, windows leak water.  Not all are leaking now, some will develop the leak later, as the window and the sealing products used to install the window age.  The leak may be an error or failure in the installation, or it could be the window itself that is leaking.  It could be a design error, water funneling off a roof over a window, such as in the photo.  The leak may only be an incidental amount of water, or it could be a major bulk water concern.  The leak may also only be active during the once every ten-year major rain fall event.  The point is windows will leak water.

Photo by Eric Strommer-Strommer Home Improvements

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The Diminishing Return of Insulation

Insulation and R-value go together like hard work and sweat.  R-value is, of course, the resistance to heat flow.  We’ve been taught to think more is better, which is true to a point.  I’m changing the insulation in the wall of my home from R-7, originally installed in 1952, to R-15, and I’m excited to see how much more comfortable my home becomes.  There is an argument that at a certain level, more insulation will cost dollars to save pennies.    At what point do we reach diminishing returns?

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Building Science-Window Condensation

As I write this blog, a good portion of the nation is experiencing very cold temperatures with high winds.  I’m currently sitting at -9°F with a windchill or feels like temp of -38°F.  Chatting with a good friend in Kansas City recently, he was impressed by the below zero temperature readings.  (He was actually begging me to stop sharing and keep the nasty weather in Minnesota.)  Because of the weather, I’ve been receiving emails and DMs on Instagram about how people’s houses are reacting to this weather extreme.  Window condensation has been one of the more frequently asked questions, so I figured I’d cover that topic in a blog post.

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Building Science-Natural Air Leakage

This blog first appeared on the Green Building Advisor website.

When conducting a blower door test, one of the ways we express the findings is with air changes per hour at 50 Pascals (ACH50).  As an example, a new home is blower door tested and found to be 2.75 ACH50, this means the entire volume of air inside the home is exchanging with the outside air 2.75 time per hour at the test pressure of 50 Pascals.  When discussing blower door testing with builders and homeowners, it can be hard for them to relate to the ACH50 number other than they know the home needs to be less than a certain level of air tightness to meet current code requirements.  Expressing the tightness as natural air leakage can sometimes be helpful.  How can we calculate the natural air change rate?  Well, there’s a formula:

ACH50/n-Factor = ACHnat Continue reading “Building Science-Natural Air Leakage”

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Building Science-Tight Homes and Negative Pressures, When Should We Be Worried?

This post originally appeared on the Green Building Advisor Website.

A couple years ago I was asked to perform a blower door test on a new home.  The home was small with a footprint of only 1130 square feet.  When the test was completed, the test report indicated an air leakage rate of 91 CFM at the test pressure of 50 Pascals, .33 ACH50.  Completely unexpected for this code-built house.  (I actually measured the volume of the home again and ran the test two more times before I was convinced I had an accurate test.)  The contractor contacted me some time later and indicated the homeowners were noticing air coming through the exterior light switches when the dryer was operating.  The dryer was producing close to the same negative pressure as my blower door every time it was being used, a negative pressure of about 50 Pascals.  Is this a problem?

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