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Choosing a New HVAC System

A homeowner looks for suggestions in updating old heating and cooling equipment

Posted on Feb 5 2018 by Scott Gibson

Jill D has done her homework, and now it's time to choose a new heating and cooling system for her Climate Zone 5B home.

There are three distinct zones to consider: the main house, a sunroom addition, and an office addition. Neither the office nor the sunroom is ducted, although heating and cooling loads there are relatively low. In the main house, the heating loadRate at which heat must be added to a space to maintain a desired temperature. See cooling load. has been calculated at between 28,000 and 36,000 BtuBritish thermal unit, the amount of heat required to raise one pound of water (about a pint) one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match. One Btu is equivalent to 0.293 watt-hours or 1,055 joules. per hour, and the cooling load at between 24,000 and 36,000 Btu per hour.

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Image Credits:

  1. Green Mountain Power

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Air Conditioner Performance In Extreme Heat

Will our residential cooling units still perform well in a future that includes extended heat waves?

Posted on Jul 14 2017 by Martin Holladay

During the last week of June, many major U.S. news outlets sent reporters to Arizona to issue updates on the area’s extreme heat wave. Outdoor temperatures hit 119°F in Phoenix. Some airplanes were grounded because the hot air was too thin for small jets to take off. Car steering wheels were so hot that some drivers wore oven mitts. VinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). records delivered by mail arrived warped. Emergency room physicians reported an increase in burn cases: hands were burned when people touched their cars, and children’s feet were burned when they went barefoot outdoors.

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Image Credits:

  1. Proctor Engineering Group

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Airport House: Heating and Cooling

Insulation levels play a role in selecting the most appropriate system

Posted on Mar 30 2017 by Reid Baldwin

Editor’s note: This is one of a series of guest blogs by Reid Baldwin about the construction of his house in Linden, Michigan. You can read his entire blog here.

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Image Credits:

  1. Reid Baldwin

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This Radiative Cooling Material Could Supplant Traditional Air Conditioners

A new study shows a breakthrough in the cooling effect of a material that’s easy to manufacture

Posted on Feb 22 2017 by Allison A. Bailes III, PhD

When it's hot out, we want cold. At night, we like to be able to turn on the lights. During the daytime, it can be hard to find the darkness.

All these things — hot and cold, day and night, light and dark — can seem like opposites. Chinese philosophy suggests, however, that these opposing forces, known collectively as the yin and the yang, aren't separate. And science has proved it. Let me tell you about the latest yin and yang science and how it could revolutionize air conditioning.

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Image Credits:

  1. University of Colorado at Boulder

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My House is Too Hot

Solutions for homes that just won’t cool off

Posted on Aug 12 2016 by Martin Holladay

During the summer, your house is too hot. What’s the solution?

The simplest thing to do, of course, is to get a bigger air conditioner. That crude solution certainly works: if you blast enough cold air into a building — even a leaky, poorly insulated building — you can lower the indoor air temperature. (Of course, adopting this approach is no guarantee of success, since central air conditioning systems are often poorly designed and haphazardly installed.)

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Image Credits:

  1. Karyn Patno

Stop Ceiling Fan Blade Wobble

In this video, Fernando Pages Ruiz shows you how to balance the blades of a ceiling fan to eliminate wobble.

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Ceiling fans are a great way to create more comfort in a room by circulating either warm or cool air to average out the temperature. When installing them, it is important to make sure the blades are balanced. While this is typically done at the factory, fine adjustment is sometimes needed. In this video Fernando Pagés Ruiz shows you how to use the balancing tool that comes along with the fan.

Video by: Gary Junken

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Choosing a Base Temperature for Degree Days

This reference point is important when using degree days for energy consumption analysis

Posted on Dec 17 2014 by Allison A. Bailes III, PhD

Degree days are a combination of time and temperature. We looked at their uses and where they come from in Part 1 of this series, and now it's time to go a little deeper.

The temperature enters as a temperature difference, ΔT (delta T), but it's not the ΔT between inside and outside of the building. It's the difference between the outdoor temperature and the base temperature. But what is this thing called base temperature?

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Image Credits:

  1. Hans Splinter, from

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Why Is My House So Hot?

A GBA reader believes that after he added more attic insulation, his air conditioning equipment runs longer than it used to

Posted on Aug 11 2014 by Scott Gibson

When Jeff Watson realized that the insulation on his attic floor was rated at R-11, he did what any energy professional would have suggested: he added more insulation. He air sealed the attic floor, added ventilation baffles where necessary, and blew in a thick layer of R-60 insulation. But he isn't entirely satisfied at the results.

"As expected, the temperature in the house doesn't fluctuate as much," Watson writes in a Q&A post at GreenBuildingAdvisor. "However, I feel as if I'm using AC more.

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Image Credits:

  1. Dennis Schroeder/National Renewable Energy Laboratory

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High-Tech Ceiling Fans for Low-Tech Cooling

The sleek, energy-efficient Haiku fan from Big Ass Fans will help keep us comfortable in our new house this summer

Posted on May 15 2014 by Alex Wilson

Winter has barely ended in Vermont, but as I write this the forecast is for 82 degrees tomorrow. This makes me think about strategies for keeping cool in the months ahead. I’m looking forward to trying out the high-tech ceiling fans we installed in our two upstairs bedrooms. I’ll get to those fans in a minute, but first I’ll explain why I like ceiling fans so much.

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Image Credits:

  1. Images #1 and #2: Alex Wilson
  2. Image #3: Big Ass Fans

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How to Buy an Energy-Efficient Ceiling Fan

Reading the label helps, and so does avoiding bad advice

Posted on May 14 2014 by Allison A. Bailes III, PhD

A little over a decade ago when I was building a house and buying a bunch of ceiling fans, it wasn't so easy to figure out which fans were energy efficient and which weren't. That's not the case anymore because every ceiling fan now has a label on the package that tells you how much air movement you can expect for each watt of electricity you put into the fan.

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Image Credits:

  1. Image #1: Kevin Marsh
  2. Image #2: Energy Vanguard
  3. Image #3: Energy Vanguard
  4. Image #4: Energy Star
  5. Image #5: Big Ass Fans

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