Musings of an Energy Nerd

Zehnder Develops a Ductless ERV

Posted on September 30, 2016 by user-756436

Anyone who lives in a tight house needs a ventilation system. Unfortunately, most ventilation systems are expensive. If you decide to install a high-quality heat-recovery ventilator (HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. ) or energy-recovery ventilator (ERV(ERV). 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.) with dedicated ductwork, your ventilation system might cost you between $6,000 and $8,000.

Adopting a Green Lifestyle

Posted on September 23, 2016 by user-756436

I’ve always struggled with the word “green.” I’m not quite sure what “green building” means, but most definitions include the idea of environmental responsibility.

To get a better handle on environmental responsibility, it might be useful to create a list of green values or aims. Here’s my stab at creating such a list.

Green values include:

  • Avoiding actions that injure biodiversity.
  • Avoiding actions that destroy important habitat, especially habit for threatened species.
  • Avoiding actions that increase the likelihood of species extinction.

Indoor Microbes and Human Health

Posted on September 16, 2016 by user-756436

The word “health” is usually reserved for living things. Our children can be healthy or unhealthy, and so can our pets and the apple trees in the back yard. But what’s a “healthy house”?

Most people use the phrase “healthy house” to describe a house that either promotes the health of the occupants or, at a minimum, doesn’t make the occupants sick. Of course, everybody wants a healthy house: Who wants to live in a house that makes you sick?

A Web-Based Information Resource From the DOE

Posted on September 9, 2016 by user-756436

The Building America program, a branch of the U.S. Department of Energy, funds research on ways to improve the energy performance of new and existing homes and provides advice to new home builders and home-performance contractors. In recent decades, Building America has provided millions of dollars of research grants to energy consulting companies, including the Building Science Corporation, Consol, Florida Solar Energy Center, IBACOS, 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. Institute U.S., and Steven Winter Associates.

Being a Carpenter Isn’t Simple Anymore

Posted on September 2, 2016 by user-756436

After working for years as a carpenter, Bart Laemmel, a resident of Crested Butte, Colorado, decided to upgrade his skills. “I have a thirst for knowledge,” he said. Speaking at a presentation at the recent Westford Symposium on Building Science, Laemmel deployed his self-deprecating humor. “I am a HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. rater,” he said. “It was an intense training — seven days straight. I figured I knew everything. And I am a LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. professional. I know how to check stuff off.”

High Humidity in Unvented Conditioned Attics

Posted on August 26, 2016 by user-756436

If you convert your vented unconditioned attic to an unvented conditioned attic by installing open-cell spray foam on the underside of your roof sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. , you may be surprised to discover that your attic is now the most humid room in your house.

Why? We don't know. Although building scientists haven’t achieved a consensus on the answer, we do have enough information to paint a picture of what’s going on.

Attaching Corner Trim on Walls With Rigid Foam

Posted on August 19, 2016 by user-756436

Many readers have built homes with 4 inches or 6 inches of rigid foam on the exterior side of their walls. Typically, these walls include vertical 1x4 furring strips, 16 inches or 24 inches on center, on the exterior side of the rigid foam. The furring strips perform at least three functions: they hold the foam in place, they create a rainscreenConstruction detail appropriate for all but the driest climates to prevent moisture entry and to extend the life of siding and sheathing materials; most commonly produced by installing thin strapping to hold the siding away from the sheathing by a quarter-inch to three-quarters of an inch. gap, and they provide something for the siding to be fastened to.

My House is Too Hot

Posted on August 12, 2016 by user-756436

During the summer, your house is too hot. What’s the solution?

The simplest thing to do, of course, is to get a bigger air conditioner. That crude solution certainly works: if you blast enough cold air into a building — even a leaky, poorly insulated building — you can lower the indoor air temperature. (Of course, adopting this approach is no guarantee of success, since central air conditioning systems are often poorly designed and haphazardly installed.)

Capillary Breaks Above Footings

Posted on August 5, 2016 by user-756436

Builders routinely install several types of barriers to avoid damp basements. Examples of these features include a layer of crushed stone and polyethylene under a basement slab; asphaltic dampproofing on the exterior side of basement walls; and sill seal made of thin closed-cell foam between the top of a foundation wall and the mudsill. All of these materials are used to reduce the transfer of moisture from the damp soil surrounding a foundation to the interior of the building or vulnerable framing lumber.

Batteries for Off-Grid Homes

Posted on July 29, 2016 by user-756436

Is solar electricity cheap or expensive? There are two parallel stories circulating these days. One version of the story — the older of the two — is that electricity from 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 is more expensive than grid power, and that adding batteries makes PV even more expensive.

The newer tale, oft-repeated on, is that PV is cheap and getting cheaper, and that any utility that tries to limit PV installations is doomed to failure — because homeowners who are disgruntled by a PV-hostile utility will choose to install batteries, cutting the cord to the grid.

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