The most recent blogs at Green Building Advisor

The Physics of Water in Porous Materials

Posted on May 6, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

I like to tell people I'm a recovering academic. The truth is, though, that I haven't left physics behind. That would be impossible since I've been making a career in the world of building science. So today I'm going to delve into that subset of building science called building physics as we take a look at the physics of water in porous materials. You'll also learn about the fourth state of water, the one that's not liquid, not solid, and not vapor.

Steve Mouzon on the New Business of Business

Posted on May 5, 2015 by Fernando Pages Ruiz in Guest Blogs

The green-building movement proved resilient during the Great Recession and beyond. While conventional builders went bankrupt, many green builders thrived. This trend continues, so when I heard that green-building guru Steve Mouzon, author of The Original Green, was holding a seminar on new approaches to building up green business, I wanted to know more.

I spoke with Steve while he was on the road in Birmingham, Alabama, and I asked him, "What's different about the new green business plan from the traditional builder's approach?"

The 2015 Passive House Conference in Germany

Posted on May 4, 2015 by Ken Levenson in Guest Blogs

The 19th Annual International 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. conference was held in Leipzig, Germany, on April 17-18, 2015. With large contingents attending from North America and China, as well as an emerging group of practitioners stretching across the Mediterranean from Turkey to Portugal, the global effort of Passive House was palpable.

Compared to previous years, project types continue to expand, from factories, to office complexes to day-care centers. So do the details: optimizing thermal bridges, earthquake load requirements, incorporating wood-fired furnaces, and onsite renewables.

New Life for Old Double-Hung Windows

Posted on May 4, 2015 by John Michael Davis in Green Building Blog

A client recently complained to me about how badly the old windows rattled in his historic home. He wanted to stop the noise as well as the air infiltration, but he didn’t want me to replace the windows. Like me, my client understands the important role that original windows play in preserving an older home’s historical integrity.

Using a Tankless Water Heater for Space Heat

Posted on May 1, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

You can buy a gas-fired tankless water heater for $600 — or even $300, if you want a bare-bones model. These appliances are remarkable: they are compact enough to hang on a wall and can begin producing an “endless” flow of hot water almost instantly. Many people look at these small appliances and think, “Why can’t I use one to heat my house?”

The answer is, you can. However, just because you can, doesn’t mean you should.

The Smart Meter: Friend or Foe?

Posted on April 30, 2015 by Emma Bailey in Guest Blogs

Love them or hate them, smart meters are becoming increasingly common around the globe.

Advocates believe that the meters generate better data for both energy consumers and service providers. These meters can provide homeowners with feedback on their energy consumption, which helps them change their habits in order to reduce monthly utility bills. Critics, however, have voiced concern over health and safety issues, asserting that smart meters present fire hazards, emit dangerous levels of radiation, and violate privacy.

Rainwater Collection Lowers the Impact on a Coastal Site

Posted on April 30, 2015 by Stephen Sullivan in Green Building Blog

I was honored when longtime friend Laura Sewall invited me to design her house at Small Point, Maine. Set at the mouth of the Sprague River as it spills into the Atlantic, the site witnesses the daily ebb and flow of the ocean’s tides in a vast estuary. Laura saw this dramatic site, the setting for generations of family summer retreats, as a precious gift from her ancestors.

Lstiburek’s Ideal Double-Stud Wall Design

Posted on April 29, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Joe Lstiburek called me last week to set the record straight. I had written an article about a study of moisture in double-stud walls in a Massachusetts home, and his company, Building Science Corporation (BSC), had done the research as part of the Building America program. They found elevated moisture content in the cold, exterior sheathing, and Joe wanted to make sure everyone knew, "I would never build that wall because I consider it too risky."

New Passive House Rules Take Effect

Posted on April 28, 2015 by Scott Gibson in Green Building Blog

Until now, anyone planning to build to 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. performance standard had a single set of rules to follow. Whether you lived in San Diego or International Falls, Minnesota, buildings could use only a certain amount of energy for heating and cooling, and were allowed a very specific amount of air leakage in 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..

Is a Ground-Source Heat Pump My Best Bet?

Posted on April 27, 2015 by Scott Gibson in Q&A Spotlight

Cathleen Dalmeida is budgeting for a heating and cooling system as part of an energy retrofit and is wondering whether a 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. is part of her future. An obvious question: How much do they cost?

"Is there a general rule of thumb for pricing of a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. and air-to-water heat pump for a medium sized installation?" she asks in a Q&A post at Green Building Advisor.

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