Building Science

The Important Stuff You Need to Know About Ceiling Fans

Posted on July 11, 2018 by Allison A. Bailes III, PhD

Here we are in the middle of air conditioning season.  So why don't we chop down some myths and misconceptions about ceiling fans?

What got me on to this topic was a video of a fan with blades that hide on top of the fan when the fan is turned off. Sounds clever, but it's a ridiculous idea.

Anyway, here are seven things about ceiling fans that a lot of people seem not to know.

An Update on the Residential Ventilation Debate

Posted on June 27, 2018 by Allison A. Bailes III, PhD

It's been a while since I've written about what I had been calling "The Great Ventilation Debate" back when Joe Lstiburek was battling the ASHRAE 62.2A standard for residential mechanical ventilation systems established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. Among other requirements, the standard requires a home to have a mechanical ventilation system capable of ventilating at a rate of 1 cfm for every 100 square feet of occupiable space plus 7.5 cfm per occupant. residential ventilation committee. The 62.2 committee meets in person twice a year at the two ASHRAEAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). International organization dedicated to the advancement of heating, ventilation, air conditioning, and refrigeration through research, standards writing, publishing, and continuing education. Membership is open to anyone in the HVAC&R field; the organization has about 50,000 members. conferences, and they just met last Friday and Saturday in Houston, Texas.

A few things have happened over the past few years, so let me give you a brief update.

Do Solar Panels Need to be Cleaned?

Posted on June 21, 2018 by Peter Yost

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.

Simple Steps to Improve Air Conditioner Performance

Posted on June 13, 2018 by Allison A. Bailes III, PhD

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.

Phenolic Foam Insulation Revisited

Posted on May 24, 2018 by Peter Yost

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:

How to Read Manual J Reports

Posted on May 23, 2018 by Allison A. Bailes III, PhD

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.

Proper Sizing Isn’t the Real Reason for HVAC Design

Posted on May 9, 2018 by Allison A. Bailes III, PhD

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.

Understanding and Measuring Mean Radiant Temperature

Posted on April 26, 2018 by Peter Yost

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.”)

Sweaty Southern Slabs

Posted on April 25, 2018 by Allison A. Bailes III, PhD

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.

HVAC Design Requirements in the International Building Codes

Posted on April 11, 2018 by Allison A. Bailes III, PhD

Building codes, especially those related to energy efficiency, have improved a lot over the years. With building enclosures, this has made a big difference. We now have more insulation, less thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel. , and tested air barriers. On the mechanical side, the improvements are significant — reduced duct leakage and mechanical ventilation in airtight homes — but there's still a gap between some code requirements and what's being installed.

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