Thursday, June 21, 2018

Do Solar Panels Need to be Cleaned?

Subtitle: 
How the accumulation of dust, pollen, and bird droppings affects the energy production of a PV array
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I was at my brother’s house in Lee, New Hampshire, recently and looked up to see that his 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 looked a bit dull (see Image #2 below). His PV array is easy to get to — the long north slope of his roof has a walkable 5:12 pitch — so we went up and took a closer look.

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from Building Science http://www.greenbuildingadvisor.com/blogs/dept/building-science/do-solar-panels-need-be-cleaned

Wednesday, June 13, 2018

Simple Steps to Improve Air Conditioner Performance

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Subtitle: 
If your air conditioner struggles to keep up in the heat, these measures can help
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It's getting hot out there. Here in the Southeast, we love our air conditioning.  In fact, without air conditioning, far fewer people would live in places like Houston, Hattiesburg, and Sopchoppy. And that's true for the hot, dry places, too, like Phoenix, El Paso, and Boron.

So if we're going to have air conditioning in our homes, we want it to work.  It should be effective and efficient.  It should keep us cool without creating new problems, such as excessive noise, bad indoor air quality, or comfort that varies from room to room.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/simple-steps-improve-air-conditioner-performance

Thursday, May 24, 2018

Phenolic Foam Insulation Revisited

Subtitle: 
Can we put to bed the corrosion concerns with this insulation?
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A particularly well thought-out and thorough question from longtime GBAGreenBuildingAdvisor.com reader Aaron Birkland on the pH of phenolic foam and its possible corrosive nature prompted me to follow up my original blog on Kingspan’s Kooltherm rigid insulation.

Aaron has two main questions:

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from Building Science http://www.greenbuildingadvisor.com/blogs/dept/building-science/phenolic-foam-insulation-revisited

Wednesday, May 23, 2018

How to Read Manual J Reports

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Subtitle: 
If you know what to look for, it’s easy to check for accuracy
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When you enter the world of building science — whether through building a house, becoming a home energy rater/building analyst, or just hanging out in cyberplaces like this — everyone talks about the importance of getting actual heating and cooling load calculations based on ACCA Manual J. A great number of HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractors sell and install oversized equipment with air distribution systems that don't work because these contractors base their choices on rules of thumb.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/how-read-manual-j-reports

Wednesday, May 9, 2018

Proper Sizing Isn’t the Real Reason for HVAC Design

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Subtitle: 
Yes, size matters, but another factor matters more
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Many people seem to think HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. design means you get a load calculation (Manual J in the ACCA protocols) so you know what size system to put in. Hey, that's a great start. It's way better than just using a rule of thumb or Manual E (for eyeball).

But there's so much more to real HVAC design than simply finding out how much heating and cooling a building needs when it's at design conditions. And we might as well start with the fact that my first statement is incorrect: The load calculation does not tell you what size system you need.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/proper-sizing-isn-t-real-reason-hvac-design

Thursday, April 26, 2018

Understanding and Measuring Mean Radiant Temperature

Subtitle: 
Mean radiant temperature, a major component of thermal comfort, is easy to measure
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All the way back in 1993, one of my first research projects at the NAHBNational Association of Home Builders, which awards a Model Green Home Certification. Research Center was assessing the performance of radiant ceiling panels for the Department of Energy’s Advanced Housing Technology Program. (The final report was titled “An Evaluation of Thermal Comfort and Energy Consumption for the Enerjoy Radiant Panel Heating System.”)

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from Building Science http://www.greenbuildingadvisor.com/blogs/dept/building-science/understanding-and-measuring-mean-radiant-temperature

Wednesday, April 25, 2018

Sweaty Southern Slabs

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Subtitle: 
Here’s why wet concrete and stone in winter are common along the coast
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If you live anywhere in a warm, humid coastal area, you're no doubt familiar with wet concrete in winter. Some days you walk outside and find the carport slab is soaking wet. How did it happen? Did rain blow into the carport? If it's not rain, is it moisture from the ground that came up through the concrete? Could it be condensation from the water vapor in the air? Let's take a look.

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from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/sweaty-southern-slabs