The most recent blogs at Green Building Advisor

Today I'm going to give you three reasons why your 3 ton air conditioner isn't really a 3 ton air conditioner. Of course, there are more than three reasons, starting with the fact that it's not 3 tons in weight. That unit refers to cooling capacity and harkens back to the days of ice.

Readers are invited to identify as many errors they can spot in the attached photo of a multifamily building in Minneapolis, Minnesota.

This is the latest photo in our ongoing series, “What’s Wrong With This Picture?” (To see three previous photos in the series, click the links in the box below.)

The photo comes from Garrett Mosiman and Pat Huelman at the University of Minnesota. (Their work is funded by the Building America program.)

Most of the houses that Atlanta architect Scott West designs are contemporary, and they typically come with flat roofs. Construction often consists of 12-in. deep I-joists or open-web 2x4 trusses capped with oriented strand board (OSB) 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. . Roofs are unvented, and the use of recessed can lights is probably unavoidable.

If your home has a swimming pool, your pool pump may use more electricity than any other appliance in your home — as much as three times the electricity used by your refrigerator. Many residential pools in the U.S. have 1.5-horsepower or 2-horsepower pumps that draw 2,000 watts or more. If you’re not paying attention, you may be running your pool pump for 24 hours a day — even though your pool might be perfectly clean with only 6 hours of pump operation per day.

I’ve long appreciated the adage that you can’t manage what you don’t measure, so I’ve spent a good bit of time looking at numbers — especially relating to energy. (Apologies in advance to readers who don’t think quantitatively.)

One of those numbers that I’ve always been intrigued with is how much of our nation’s total energy consumption relates to buildings. That sounds simple enough.

A few years ago, 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 student in a class I taught told a funny story. He was an HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractor and said he was installing a new air conditioner for an elderly woman. As he was explaining things to her, he mentioned that they would be installing a 4-ton unit. "Oh, my," she said. "How are you going to get something so big into my back yard?"

I conducted my first paid energy auditing gig a few months after I’d completed the Maine State Housing’s Auditor certification program. It was a two-week program — one week of class work and one week of field training. That's just enough learning to make you dangerous (and I’m only being a little facetious; uninformed auditor recommendations can have dire consequences).

I had done three practice audits on the homes of friends and family and observed three others. However, this was the first paying audit largely on my own.

The 2013 ACI National Home Performance Conference, called Affordable Comfort until a few years back when the conference was renamed ACI, recently took place in Denver, Colorado. This year, the conference came complete with about six inches of snow in May — quite a shock for a transplanted Southerner.

If you live in a humid climate (for example, in Florida), you need an air conditioner that does a good job of dehumidification. But if you live in a dry climate (for example, in Nevada), dehumidification is almost irrelevant, because the outdoor air is so dry. In Nevada, all you need is an air conditioner that lowers the temperature of the air in an energy-efficient way.

I’m just back from a week in Seattle, where I attended the Living Future Conference, which this year had a theme of resilience and regeneration — a major focus of mine with the Resilient Design Institute. While there I visited what is almost certainly the greenest office building in America, if not the world.