Musings of an Energy Nerd

Building a Passive House for $163 per Square Foot

Posted on May 11, 2018 by Martin Holladay

A family in Wakefield, Rhode Island, recently moved into a new 1,840-square-foot Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. with three bedrooms and two bathrooms. If you exclude the cost of the lot, the architectural fees, and the cost of getting the house certified by PHIUS, the construction cost was $300,420, or $163 per square foot (if you measure the area of the house on the exterior).

The members of the team that built the house include Brad and Jordan Hevenor, the homeowners; Steve Baczek, the architect; and Stephen DeMetrick, the builder.

Another Perspective on Air-to-Water Heat Pumps

Posted on May 4, 2018 by Martin Holladay

Green builders, preparing for a fossil-fuel-free future, are busy building all-electric homes. Most of these homes are heated and cooled by minisplit heat pumps. Occasionally, though, a builder who’s worried about uneven heat distribution in a home with ductless minisplits will post a question on suggesting the use of an air-to-water heat pump hooked up to a hydronic distribution system.

Bruce Harley’s Minisplit Tips

Posted on April 27, 2018 by Martin Holladay

Bruce Harley is a Vermont energy consultant and heat-pump specialist. To readers, he is probably best known as the author of the Taunton book, Insulate and Weatherize — one of the best available books on residential energy retrofit work.

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.

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