The most recent blogs at Green Building Advisor

Determining the Best Attic Option

Posted on October 20, 2014 by Scott Gibson in Q&A Spotlight

Attics come in many shapes and sizes, but they are either conditioned or unconditioned. That is, they are insulated and heated like the rest of the house and can be considered conditioned spaceInsulated, air-sealed part of a building that is actively heated and/or cooled for occupant comfort. , or they are designed to allow the free circulation of outdoor air and become unconditioned spaces.

Is one option better than the other? That's what Rus Pearson would like to know.

Dense-Packed Cellulose and a Wrong-Side Vapor Barrier

Posted on October 17, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Does the exterior 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. on a double-stud wallConstruction system in which two layers of studs are used to provide a thicker-than-normal wall system so that a lot of insulation can be installed; the two walls are often separated by several inches to reduce thermal bridging through the studs and to provide additional space for insulation. accumulate worrisome quantities of moisture in late winter? Several researchers are now looking into this question, and Green Building Advisor has been sharing the researchers' findings as the information becomes available.

An Affordable Zero-Energy House in Massachusetts

Posted on October 16, 2014 by David Posluszny in Guest Blogs

Recently I designed and built my home in Shirley, Massachusetts. The design goal was to build a net-zero-energy house. However, it had to be comfortable to live in, easy to build with low-skilled labor, and very affordable.

I had to keep it simple because I had my family for laborers, and they do not have construction skills. The home also had to be comfortable to live in, with adequate daylightingUse of sunlight for daytime lighting needs. Daylighting strategies include solar orientation of windows as well as the use of skylights, clerestory windows, solar tubes, reflective surfaces, and interior glazing to allow light to move through a structure. and easy circulation. The budget demanded that the house be kept small, but several design tricks involving lines of sight were used to make the space feel much larger than it actually is.

The Diminishing Returns of Adding Insulation

Posted on October 15, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

If you're building a house and want to have a really good building enclosure, you need it to be airtight, handle moisture properly, and have a good amount of insulation. Ideally, you'd also consider the effects of solar radiation on the home, but for now let's just focus on the insulation. What exactly is "a good amount" anyway?

A Tale of Two Houses

Posted on October 14, 2014 by Scott Gibson in Green Building Blog

As difficult as it is to meet the requirements for Passivhaus certification, builders and designers have a great deal of leeway in how they approach it. There are just a few big hurdles to clear, including limits on how much energy the building can use and how airtight the building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. must be.

Exactly how a builder accomplishes this is not spelled out. As long as the building meets the standard, it can win certification, either from the 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. (PHIUS) or its European counterpart, the Passivhaus Institut (PHI).

Living in a Passivhaus

Posted on October 14, 2014 by Daniel Roy in Guest Blogs

[Editor's note: Daniel Roy is one of the owners of a recently completed 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. in Falmouth, Massachusetts. Designed by architect Steve Baczek, the house was featured in a series of GBA videos. For more information on the home's energy specifications, see the attached Excel spreadsheet.]

Attaching SIPs to Structural 2×6 Studs

Posted on October 13, 2014 by Alexi Arango in Guest Blogs

As they set out to build a single-family 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. on Potwine Lane in Amherst, Massachusetts, Alexi Arango and LeeAnn Kim asked themselves, “Is it possible to live without burning fossil fuels?” One measure of success would be meeting their goal of net-zero energyProducing 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. performance. This is the fifth blog in a planned series.

It’s Not About Space Heating

Posted on October 10, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

If you design a “pretty good house” with R-20 basement walls, R-31 above-grade walls, an R-49 ceiling, triple-glazed windows, a minisplit 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., and an 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. , what should you do next to reduce your energy bills? Maybe aim for the 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?

The ‘Low-Hanging Fruit’ Fallacy

Posted on October 9, 2014 by Nate Adams in Guest Blogs

First, a definition. The phrase “energy efficiency programs” (or just “programs”) refers to any utility-funded or state-funded program that offers homeowners a rebate, incentive, or inexpensive financing to make energy efficiency upgrades in their homes.

Using Server Farms to Heat Buildings

Posted on October 8, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Last week in my ASHRAE newsletter, I saw an interesting story about a cool thing that Amazon.com is planning to do with heat. Amazon, in case you didn't know, is a heavy user of computers. Not only do their run their online store but they also have a popular cloud computing service. Computers turn electricity into kitten videos, celebrity tweets, and waste heat.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!