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The UK study asserts that heat pumps should achieve an


efficiency ratio of at least 3.0, meaning


that for every unit of electricity used, three equivalent units of


heat are generated. But most of the


systems tested fell short of that mark.


Media of the Month: “Mountain Patrol” (movie). It’s


Are Heat Pumps Green?


A study suggests that 80% of heat pumps installed are not performing well. Who should take the heat?


The UK, as usual, is far ahead of us in taking real steps to reduce energy usage. They have adopted a resolution to reduce greenhouse gas emissions by 34% by 2020, (from 1990 levels). Thus the timing of a study on how well heat pumps work makes sense. The government is looking at ways to sub- sidize sustainable heating, and heat pumps are a part of that plan. Energy Saving Trust looked at both ground source and air source heat pumps at 83 sites across the UK, and found that the vast majority are not achiev- ing the levels of effi ciency they should. If that sounds a bit vague, it is. When you read the report carefully, the researchers note that heat pumps are almost always an energy-saving upgrade in homes that heat with electricity, LPG and oil. It’s only when you start to com- pare their performance with homes “on the gas grid,” that the advantages may disappear. Why? Not because heat pumps can’t compete on an effi ciency level, but because of other factors, including: Rube Goldberg Designs: The study found


that improperly sized and overly complex heat pump systems were common. Simpler sys- tems tended to perform at higher effi ciency.


www.greenbuildermag.com Complex Controls: Homeowners in many


cases had no idea how to operate their heat pump systems. Water Heating Blues: For some reason, heat


pumps used to produce hot water had lower than expected effi ciency, especially in sum- mer. The researchers determine why. Tower of Babel Trades. Often, several


independent contractors were involved with the installation of a heat pump systems. For example, a plumber, electrician, ground works contractor and heat pump installer might all do some part of the job, but no single person could then be assumed to accept liability if the unit didn’t perform as anticipated. Despite these drawbacks, the


study does not dismiss heat pumps as a green heating alternative. On one level, they’re comparing how the U.K. units perform compared with the rest of Europe, and coming up short. But on the other it’s pointing out key changes that could raise the effi ciency bar and optimize the technology. Simplify the controls. Consolidate contractors. And keep it simple.


Full Report: www.energysavingtrust.org.uk October 2010 GreenBuilder 39


not often that we recommend a motion picture as a tool to help reach a higher level of eco-consciousness, but this is the kind of film that can change your life. A dramatized documentary, it explores the story of a group of volunteers who set out to protect herds of sacred antelope that were being slaughtered by the thousands in remote areas of Tibet. Other reviewers have described them as “vigilantes,” but unlike the poachers they confront, they are reluctant to use force. More important and moving than the movie’s plot is the way the characters interact with the irreplaceable beauty and wildlife around them. With few words, they express their deep connection with the land and all of its inhabitants. If you ever wondered what the term “deep green” really means, this portrayal of a fight-to- the-death defense of nature’s wonders is the picture that explains what 1,000 words will not. And like so many of these types of struggles, the real value of their struggle was only realized after many had made the ultimate


Smart Ventilator. It might be a stretch to call the Tjernlund xchanger basement fan


“smart.” But its inventors are. They’ve figured out how to build a self-regulating basement fan for people like me, that have damp, ancient, unfinished basements that are too wet half the year. This low-tech unit consists of a couple of fans, a rugged, galvanized case, and a dehumidistat that turns them on when the cellar needs airing. I installed one in one of my basement windows in about 40 minutes. And so far, the xchanger is doing the job, keeping the humidity level at about 55% (it started close to 70%). It has built-in reverse air dampers (which


are fine, but not airtight), however I’ll probably just remove it during the dry winter months, then put it back as the spring thaw arrives. I much prefer its two 36W fans to the heavy power demand of my dehumidifier.—M. Power


Taking residential pools to the next level, page 40


A Colorado builder exceeds the Build- ers Challenge. You can, too. page 42


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