HVAC

Heating, Ventilating, Air Conditioning

Three Types of Heating and Cooling Loads

Posted on April 18,2015 by ab3 in cooling load

What is it about the number three? You've got the Three Musketeers, the Three Little Pigs, and the Three Stooges. Then there's three strikes (what every pitcher wants), three branches of government (executive, legislative, and judicial), and the three kinds of people (those who can do math and those who can't). And let's not forget three on a match, three wise men, and threepeats. Today we'll look at another big three: the three types of heating and cooling loads. Do you know what they are already?

How Replacing a Furnace Can Make You Less Comfortable

Posted on April 18,2015 by ab3 in AFUE

Let's say your trusty old furnace is at the end of its life. You've got to buy a new one, so you call your HVAC company and they rush over to make sure you don't freeze during the next cold snap. They go and take a look at your furnace and find its capacity. They come back and tell you that you have a furnace rated for 60,000 BTU per hour and then talk to you about some of the options.

Using Server Farms to Heat Buildings

Posted on April 18,2015 by ab3 in Amazon

Last week in my ASHRAE newsletter, I saw an interesting story about a cool thing that Amazon.com is planning to do with heat. Amazon, in case you didn't know, is a heavy user of computers. Not only do their run their online store but they also have a popular cloud computing service. Computers turn electricity into kitten videos, celebrity tweets, and waste heat.

How to Tell If Your Air Conditioner Is Oversized

Posted on April 18,2015 by ab3 in air conditioner

Back in 2009, I had a new air conditioner installed our condo. The previous one was an ancient 25 years old and barely limping along. It wasn't cooling much, and the summer electric bills had risen.

The Achilles’ Heel of Zoned Duct Systems

Posted on April 18,2015 by ab3 in air flow

Last week I wrote about what happens when you try to save energy by closing air conditioning registers in unused rooms. In the end, I recommended not doing it because you won’t save money and you may create some big problems for yourself, like freezing up the coil and killing your compressor. At the end of the article, I mentioned that zoned duct systems do close off registers, and that doing so can be OK with the right kind of equipment and design. But there’s one thing often done in zoned duct systems that’s rarely done well.

Is It OK to Close Air Conditioner Vents in Unused Rooms?

Posted on April 18,2015 by ab3 in air conditioner

Your air conditioner, heat pump, or furnace probably uses a lot of energy. Heating and cooling makes up about half of the total energy use in a typical house. For air conditioners and heat pumps using electricity generated in fossil-fuel fired power plants, the amount you use at home may be only a third of the total.

How Duct Leakage Steals Twice

Posted on April 18,2015 by ab3 in air leakage

Duct leakage is a big deal. It's one of the top three energy wasters in most homes (air leakage and cable TV set-top boxes being the other two). Researchers at Lawrence Berkeley National Lab found that duct systems leak on average about 10% of the supply air they move and 12% of the return air. (Download pdf and also see Dana Dorsett's comment below, #1.) In far more homes than you might suspect, the main culprit is a disconnected duct, as shown in the photo at right, but a typical duct system has a lot of other leaks, too.

Energy Efficiency Requires More Than an App on Your Smartphone

Posted on April 18,2015 by ab3 in air conditioner

When it comes to air conditioning, there are a lot of bad products and bad ideas out there. Here are a few: You can buy a cover for your condenser that could kill your compressor.

Four Ways to Find the Size of Your Air Conditioner

Posted on April 18,2015 by ab3 in AHRI

Do you know what size your air conditioner is? In the world of building science, you'll hear a lot of talk about why oversized air conditioners are a bad idea. Why? Briefly, they don't dehumidify as well, short-cycling wears them out quicker, and your home will probably be less comfortable if the air conditioner is too big. But to know if your AC is oversized, first you have to know what size it is.

The Two Main Reasons Your Ducts Don’t Move Enough Air

Posted on April 18,2015 by ab3 in air flow

Two things. Just two things in your ducts are responsible for giving the blower in your furnace or air handler a hard time. They make the blower push against more pressure, thus reducing air flow or increasing energy use, depending on blower type. They cut the amount of air that gets delivered to the rooms. And they can be reduced but not eliminated. Do you know what they are?

What Fruit Flies Taught Me About Sustainable Living

Posted on April 18,2015 by CarlSeville in fans

Last summer my house developed a fruit fly infestation, due to the fact that I had a lot of fresh fruit sitting around ripening on my counters. I recall once using aerosol bombs to get rid of them, but I figured this time around I would look for a slightly less toxic solution. A quick web search turned up details for a standard fruit fly trap, consisting of a jar with a little cider vinegar and dish soap, covered with clear plastic with a few holes in it. The flies are attracted to the vinegar, fly in, get coated with dish soap, and drown in the cider.

California Study Shows Big Savings in Home Energy Retrofits

Posted on April 18,2015 by ab3 in air flow

At the Forum on Dry Climate Home Performance earlier this year, I got to hear three building science experts talk about a really cool research project they've been working on in Stockton, California. Bruce Wilcox, John Proctor, and Rick Chitwood (Wilcox and Proctor are shown in photo at right) filled us in on the Stockton project, which now has two years of data and shows some really impressive results.

Can’t Anyone Get Things Right?

Posted on April 18,2015 by CarlSeville in duct

In my business of certifying buildings, most of my work involves working with architects, contractors, and trade contractors who are trying to create green buildings. Unfortunately, they frequently miss the mark in some key areas. Many of them are well intended but don’t have a broad enough view of their projects. Others only do the minimum required to meet a green building standard forced on them by someone else. And a few, thankfully, seem to get it and work hard to do the right things. This post, the first in a series about problems I run across, will focus on HVAC.

New Englanders Love Heat Pumps

Posted on April 18,2015 by ab3 in air-source heat pump

Last week I went to NESEA's Building Energy conference, and I think I heard three terms more than any others: heat pump, net zero, and passive house. (The second most popular trio was beer, wine, and whisky, but that may have something to do with the folks I was hanging out with.) So let's get right to the important question here: Why do these people in the cold climate of New England love heat pumps so much?

HVAC for a ‘Pretty Good House’

Posted on April 18,2015 by ScottG in ductless minisplit

Matt Mesa is looking ahead to retirement in a new, one-level house in Hood River, Oregon. It's going to be a Pretty Good House, a phrase coined to describe a well-insulated house of an appropriate size.

How to Make Your Dumb Heat Pump Defrost Intelligent

Posted on April 18,2015 by ab3 in air-source heat pump

Heat pumps can get frosty when they run in heating mode. It doesn't happen all that often, but it's a fact of life when you're trying to extract heat from cold, outdoor air.

Should Home Builders Pay the Energy Bills?

Posted on April 18,2015 by ab3 in energy bill

Three questions have been nagging at Rick Chitwood over the past 5 or 6 years. First, why is the HVAC industry in California, where he lives and works, so pathetic? Second, why have California’s strict energy standards, which have been in effect since 1978, not corrected the problem? Third, how is it that he, who came to the HVAC business through a nontraditional route, has become a leader in the industry?

A Post-Passivhaus Paradigm for Energy-Efficient Design

Posted on April 18,2015 by user-1018844 in cooling

Last night, I enjoyed an intense conversation with my friend Bill Updike. Bill, who has been closely following the developing partnership between PHIUS and Building Science Corporation, is the green building specialist at the Washington, D.C. Department of the Environment. We were talking about cost-effective energy-efficient design, and Bill tossed off a comment that the key to any design — at least in our mixed-humid climate here in Maryland — should be the latent load of the building. When he said that, my mind lit up like a pinball machine showing three cherries.

Should Occupants Have Control of Their Home Ventilation System?

Posted on April 18,2015 by ab3 in HVAC

One of the points of contention in the great ventilation debate is whether a home's occupants should control their own ventilation systems.

Will a Gas Furnace Dry Out a Home’s Air?

Posted on April 18,2015 by ab3 in furnace

I get asked from time to time if a gas furnace dries out the air in a home and makes a humidifier necessary.

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