Musings of an Energy Nerd

Henri Fennell’s Advice on Cathedral Ceilings

Posted on April 20, 2018 by Martin Holladay

I first interviewed Henri Fennell, the celebrated spray foam consultant from North Thetford, Vermont, about twenty years ago. Back then, Joe Lstiburek, the founding principal at Building Science Corporation, called Henri “the foam god.” While Fennell’s former company, Foam-Tech, closed up shop years ago, Fennell hasn’t retired. He now works as a consultant, specializing in problems related to spray foam insulation or air leakage.

Exterior Insulation for an Ugly Brick Building

Posted on April 13, 2018 by Martin Holladay

How do you insulate an old building with exterior walls made of structural brick? The best approach, according to building science professor John Straube, is to install a continuous layer of exterior insulation. Straube told me, “It’s a great solution for ugly buildings.”

Reports from Owners of High-Performance Homes

Posted on April 6, 2018 by Martin Holladay

At Green Building Advisor, we urge readers who are planning to build a new home to seek out a builder who understands energy-efficient construction methods. Is this advice easy to follow? And once the new owners move into their energy-efficient home, are they happy with the home’s performance?

Newspapers Trumpeted ‘Solar Homes’ in the 1940s

Posted on March 30, 2018 by Martin Holladay

What’s a “solar house”? The phrase has been used since the 1940s to refer to a house with lots of south-facing glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill. — a type of house later called a “passive solar house.” The phrase is also used to refer to homes that include an active solar thermal system (one with collectors on the roof, along with pumps or fans). Finally, the phrase has recently been applied to homes with a 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.) array on the roof.

Marc Rosenbaum’s Monitoring Results

Posted on March 23, 2018 by Martin Holladay

At a recent conference in Burlington, Vermont, energy consultant Marc Rosenbaum shared insights that he’s gleaned from several energy monitoring projects. His presentation on February 7, 2018, was part of Better Buildings By Design, a conference sponsored by Efficiency Vermont.

Rosenbaum believes that energy retrofit specialists should regularly measure energy use. “We’re practitioners,” Rosenbaum told the Burlington audience. “Most of the time we try to get it right, and when we don’t we want to know why. So we grind through it. We try it again and test it.”

Preventing Frost Buildup in HRVs and ERVs

Posted on March 16, 2018 by Martin Holladay

Manufacturers of heat-recovery ventilators (HRVs) and energy-recovery ventilators (ERVs) know that HRV or ERVEnergy-recovery ventilator. The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV. cores can get clogged with ice in cold temperatures. During the winter, this type of appliance brings cold outdoor air in close proximity to a stream of humid indoor air. If the outgoing air is humid enough, and the incoming air is cold enough, the moisture in the exhaust air stream can turn to ice.

Carbon Emissions By the Construction Industry

Posted on March 9, 2018 by Martin Holladay

Burning fossil fuels or using electricity results in carbon dioxide emissions (unless the electricity is produced by photovoltaics, wind, or another renewable energy source). Since CO2 emissions cause global climate change, environmentally conscious builders aim to build energy-efficient buildings.

Finally, a Right-Sized Furnace

Posted on March 2, 2018 by Martin Holladay

For years, builders of energy-efficient homes have been frustrated by the lack of low-load furnaces. An article I wrote in 2013 about this problem began with this question: “Why are the smallest available American furnaces rated at about 40,000 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. /h?”

A 40,000 Btu/h furnace is likely to be more than twice the size of what is needed to heat a small energy-efficient home. Many homes in this category have a design heat load of only 12,000 or 15,000 Btu/h.

Looking Back at Insulating Advice from 1951

Posted on February 23, 2018 by Martin Holladay

Up until the mid-1950s, almost every American carpenter had heard of Audels Carpenters and Builders Guide. Even carpenters who didn’t own all four volumes of the book series had probably studied the Audels books at some point in their careers, or knew someone on the job site who had copies of the books.

In a way, the Audels Guide was the Fine Homebuilding of the 1930s and 1940s. It instructed beginners in the right way to do things; it upheld standards; and it promoted quality work.

Using a Bath Fan to Equalize Room Temperatures

Posted on February 16, 2018 by Martin Holladay

On Green Building Advisor, readers regularly ask questions about room-to-room temperature imbalances — the type of imbalances that may occur when a home has a point-source heater like a ductless minisplit or a wood stove. Here’s a typical question: “I’d like to install a bathroom fan to move air from a warm room to a cool room. Will this approach be enough to equalize the temperatures between the two rooms?”

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