Wednesday, November 15, 2017

The Four Laws of Thermodynamics

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We often talk of the second law, but what are the other three?
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Building science is an odd subject. Few colleges and universities teach it. The majority of those who work on buildings call themselves engineers, architects, and contractors, not building scientists. And many of those who do invoke the term can explain at least one implication of the second law of thermodynamics (we'll get to that below) but may not know what the other laws of thermodynamics are, why their numbering is so peculiar, or even how many there are. Do you?

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/four-laws-thermodynamics

Wednesday, November 8, 2017

How Many Tons of Air Does a 2.5 Ton Air Conditioner Move?

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And under what conditions would it move exactly 2.5 tons of air?
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We live in this invisible stuff called air. (But of course you knew that.) We pump it into and out of our lungs. We exhaust it from our bathrooms and kitchens. We cycle it through our heating and air conditioning systems. If we're lucky, we live in a home that even brings outdoor air inside as part of a whole-house ventilation system. But we're missing something.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/how-many-tons-air-does-25-ton-air-conditioner-move

Thursday, October 26, 2017

Water Tables and Basements

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How to use geologic, soil, and historical maps to keep your basement dry
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When we bought our home (built in 1907), I called in a favor from an electrician friend of mine to upgrade the 60-amp to a 100-amp service. Having worked together in New Hampshire where many of our projects were on sites full of ledge, he smirked when he told me: “Here, you go try and drive this 12-foot copper grounding rod.”

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from Building Science http://www.greenbuildingadvisor.com/blogs/dept/building-science/water-tables-and-basements

Wednesday, October 25, 2017

When Are Door Undercuts Sufficient for Return Air?

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You don’t always need to install individual returns, transfer grilles, or jumper ducts
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Most people don't know that simply closing a door in their home can make them sick, increase their energy bills, or reduce their comfort. We live in this invisible stuff called air. We pull many pounds of it into our lungs each day. A typical air conditioner, heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump., or furnace easily moves 20 tons of air a day. (Yes, I'm talking about 40,000 pounds! We'll save that calculation for another day, though.) And the simple act of closing a door changes the dynamics of a house in ways that can have profound impacts on the people inside the home.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/when-are-door-undercuts-sufficient-return-air

Wednesday, October 18, 2017

An Easy Retrofit for Return Air

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For homes without dedicated return grilles in the bedrooms, this easy-to-install device provides a return air pathway
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Your bedroom really doesn't aspire to be a balloon. Yet, because of the way your heating and air conditioning system was installed, it may be acting like one. At least to an extent. It doesn't expand the way a balloon does, but it does get blown up.

Think about it. If your bedroom has a supply register from your HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. system but no return grille or other pathway for the air to make its way back to the unit, what happens to that air blowing into the room when you close the door?

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/easy-retrofit-return-air

Wednesday, October 11, 2017

Four Sources of Crawl Space Moisture

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To stop moisture problems in vented crawl spaces, you have to know where the moisture comes from
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Here in the southeastern U.S., we have a lot of crawl spaces. Most are vented. Even most new ones are vented. It's not because it's the best way to keep them dry. That's certainly not true. We have enough research on crawl spaces to know better. No, they're vented because foundation vents got into the code decades ago and, once there, they’ve been difficult to dislodge.

So if you have a vented crawl space, especially in a humid climate, it most likely has moisture problems. And where does that moisture come from? Let's take a look.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/four-sources-crawl-space-moisture

Wednesday, October 4, 2017

The Difficulties of Third-Party HVAC Design

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How do we get everyone on the same page?
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What if a builder refused to build from plans drawn by an architect? What if a tile installer refused to implement designs handed to them and instead did their own thing? What if an HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractor told a potential client they wouldn't install a system designed by a third party to ACCA protocols?

One of those questions is more real than the others. Of course builders build from architects' plans and tile installers don't throw out designs they're asked to implement. But third-party HVAC design is a different animal.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/difficulties-third-party-hvac-design