Musings of an Energy Nerd

A Balanced Ventilation System With a Built-In Heat Pump

Posted on March 13, 2015 by Martin Holladay, GBA Advisor

A small manufacturing company in Illinois called Build Equinox has developed a new ventilation appliance called the Conditioning Energy Recovery Ventilator, or CERV. Build Equinox was founded by an engineer, Ty Newell, and his son Ben Newell. (Ty Newell designed and built the Equinox House, which was described in a GBA article published in 2011.)

NESEA Conference Highlights

Posted on March 6, 2015 by Martin Holladay, GBA Advisor

BuildingEnergy, the annual conference sponsored by the Northeast Sustainable Energy Association (NESEANorth East Sustainable Energy Association. A regional membership organization promoting sustainable energy solutions. NESEA is committed to advancing three core elements: sustainable solutions, proven results and cutting-edge development in the field. States included in this region stretch from Maine to Maryland. www.nesea.org), recently concluded in Boston. As usual, the NESEA conference was a great way to catch up with friends and to soak up information offered by some of the smartest scientists, engineers, designers, and builders in the country.

Here are notes from some of the presentations.

Ice Dam Basics

Posted on February 27, 2015 by Martin Holladay, GBA Advisor

What do you call the weeks between Valentine’s Day and Easter? It’s ice damA ridge of ice that forms along the lower edge of a roof, possibly leading to roof leaks. Ice dams are usually caused by heat leaking from the attic, which melts snow on the upper parts of the roof; the water then refreezes along the colder eaves working it's way back up the roof and under shingles. season, of course. Eastern Massachusetts is now the wet-ceiling capital of the world, but this winter, tens of thousands of homeowners from North Dakota to Maine are struggling with ice dams.

Designing for the Future

Posted on February 20, 2015 by Martin Holladay, GBA Advisor

When an architect, residential builder, and owner sit around a table for their first design meeting, their ostensible goal is to begin designing a house. Whether they realize it or not, however, these three people are also predicting the future.

The Evolution of Superinsulation

Posted on February 13, 2015 by Martin Holladay, GBA Advisor

At the recent “Better Buildings By Design” conference in Burlington, Vermont, I attended presentations that epitomized two different approaches to energy-conscious building. I’ll call these two approaches “classic superinsulation” and “the net zeroProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. Calculating net-zero energy can be difficult, particularly in grid-tied renewable energy systems, because of transmission losses in power lines and other considerations. approach.”

The “classic superinsulation” method has been around for about 35 years. It’s the approach that formed the basis of Wolfgang Feist’s PassivhausA 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. standard.

Split-System Heat-Pump Water Heaters

Posted on February 6, 2015 by Martin Holladay, GBA Advisor

Heat-pump water heaters are a type of air-to-water heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump.. Almost all heat-pump water heaters sold in the U.S. extract heat from the air in the room where the water heater is located, transferring the heat to water in an insulated tank.

Rules of Thumb for Ductless Minisplits

Posted on January 30, 2015 by Martin Holladay, GBA Advisor

Since 2008, when Carter Scott built a pioneering Massachusetts house that was heated and cooled by just two ductless minisplits, GBAGreenBuildingAdvisor.com has endeavored to publish reports from the field to guide people designing homes that are heated and cooled by ductless minisplits. We’ve learned a lot on this topic since 2008.

Simple Methods for Measuring Air Flow

Posted on January 23, 2015 by Martin Holladay, GBA Advisor

To commission a ventilation system or a forced-air heating system, or to troubleshoot problems with these systems, it’s essential to be able to measure the rate of air flow through registers and grilles. Most home performance contractors measure air flow with a flow hood. Flow hoods vary in accuracy, but they all share one attribute: they are expensive (generally $1,600 to $3,200).

If you want to measure air flow, but you can’t afford a flow hood, you may be interested in using one of the inexpensive approaches to air flow measurement described in this article.

What is Comfort?

Posted on January 16, 2015 by Martin Holladay, GBA Advisor

Buildings have had central heating for only about 140 years, and they have had air conditioning for only about 80 years. For most of human history, people took comfort in winter from a stone fireplace — somewhere to heat up a kettle or warm one’s hands.

Once heating and cooling systems were developed, almost everyone wanted them. Why? Because people want to be comfortable.

Building a Foam-Free House

Posted on January 9, 2015 by Martin Holladay, GBA Advisor

Many green builders want to build a foam-free house — that is, a house without any rigid foam insulation or spray foam insulation.

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