The most recent blogs at Green Building Advisor

Home energy audits in cold, northern climates are very different from those in hot climates. Different regions of the country have different types of housing stock, and there are regional variations in insulation methods and mechanical systems. In older houses, the type of weatherization work that has been performed varies greatly from region to region.

So the issues and energy priorities of northern houses are different from those of southern houses.

Construction projects are becoming more complex, with increasing levels of regulations, more product choices, and higher performance expectations. And there are so many more ways of getting bombarded with information — e-mail, text, voice-mail — that we get swept up into survival mode of responding to the bits of info as it comes along.

But the danger of this multi-tasking is that it doesn’t really work: you lose sight of the big picture (only seeing one piece of the elephant), and there is really no one who has a handle on the whole situation.

Why are the smallest available American furnaces rated at about 40,000 Btuh? Back in the 1960s, a house in a cold climate may have needed such a powerful furnace — or even one rated at 60,000 or 80,000 Btuh. But these days, many new homes have design heating loads that are much smaller — as low as 10,000 to 20,000 Btuh. Over the past 30 years, building envelopes have become tighter and better insulated, but U.S. furnace manufacturers haven’t kept up with the times. For mysterious reasons, they don’t offer furnaces that are small enough for today’s energy-conscious builders.

A few weeks ago I spent a half day with my good friend Tedd Benson learning about his new company Unity Homes. This Walpole, New Hampshire company is on the cutting edge of home building today, with its focus on energy performance, building science, green building, and (relative) affordability.

This week I’ll describe some of Tedd’s work that ledLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. to the creation of Unity Homes, and next week I’ll go into more detail about this new company and the state-of-the-art green homes that he and his team are cranking out.

Occasionally I get asked if it's OK to put the condensing unit of an air conditioner or 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. in a garage or other room that's a buffer space. The thinking is that since the temperature may not be as hot in summer or as cold in winter, the system will operate more efficiently.

I saw recently that this same question came up in a column in Home Power magazine, so I thought this would be a good time to cover this issue (once and for all?) here.

One thing that sets my teeth on edge as an energy auditor is when folks assume that a new home won’t have energy problems or be inefficient. A friend recently mentioned that weatherization and efficiency work must have a great market with Maine’s old housing stock but would be pointless in new homes. Commence ripping out hair.

As Steven Knapp and his wife plan a new house in Atlanta, indoor air quality (not energy efficiency) is at the top of their priority list. At least that's how a recent discussion on autoclaved aerated concrete began.

Green building websites can be confusing. One site might tell you that a green home should include spray foam insulation, a tankless water heater, and a geothermal heating system. After you’ve absorbed this advice, you visit another website, where you learn that spray foam is a dangerous petrochemical, tankless water heaters are overpriced gadgets, and “geothermal” systems aren’t really geothermal.

Getting back to our Dummerston, Vermont farmhouse this week, I’m reporting on our use of a relatively new product for air-sealing homes: EcoSeal from Knauf Insulation.

First some context: In the building science world, there is growing interest in achieving a robust air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both. at the 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. layer of a house, with layers inside of that able to dry toward the interior and layers on the outside able to dry to the exterior. To make that work, the sheathing layer has to be tightly air-sealed.

GBAGreenBuildingAdvisor.com has released two new videos: one on installing dense-packed cellulose in stud cavities, and the other on sealing duct seams with mastic.

Both videos were recorded in March 2013 at 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's Building Energy 13 conference in Boston.