Musings of an Energy Nerd

How Balanced Ventilation Systems Become Exhaust-Only

Posted on June 20, 2014 by Martin Holladay, GBA Advisor

Unlike the homes of our great-grandparents, the homes of most Americans are served by an array of automatic appliances and systems.

When our great-grandparents returned home after a three-day absence, they would need to haul a bucket of water from the spring and light a fire in the kitchen stove before they could brew tea. Today’s homes, of course, have electricity for lighting, a furnace for warmth, an air conditioner for cooling, a water heater for showers, and internet access for Googling.

Universal Design

Posted on June 13, 2014 by Martin Holladay, GBA Advisor

Why are most interior doorways only 30 inches wide? Why are so many doorknobs hard to grip? And why do so many homes have a long stairway between the front door and the bedrooms?

Two typical answers to these questions would be, “because that’s the way we’ve always built houses” and “because these houses meet code.” (Those two reasons happen to be pretty weak, by the way.)

Vermont House Uses Only Half a Cord of Firewood

Posted on June 6, 2014 by Martin Holladay, GBA Advisor

When my friend Laura Murphy mentioned that her neighbors in Ripton, Vermont, Chris and Zoe Pike, stayed warm last winter by burning just half a cord of firewood, I was intrigued. So I tracked down the Pikes to learn a few more details about their house.

New Green Building Products — May 2014

Posted on May 30, 2014 by Martin Holladay, GBA Advisor

It’s time once again to take a look at a few interesting new building products. I recently spotted two potentially useful ventilation products — a new type of 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. and a fan for ventilating small rooms — and two products that are destined for attics — an insulating “hat” for recessed cans and a ventilation baffle that can be installed between rafters. I will also report on JointSealR, a tape distributed by Owens Corning for taping XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation. seams.

Earthship Hype and Earthship Reality

Posted on May 23, 2014 by Martin Holladay, GBA Advisor

If you are a hippie from Taos, New Mexico, you know what an earthship is. It’s an off-grid earth-bermed passive solar home with exterior walls made of old tires packed with dirt.

Solar Hot Water System Maintenance Costs

Posted on May 16, 2014 by Martin Holladay, GBA Advisor

I installed my solar hot water system about six years ago. It’s a good system. I have two 4’x8’ AE-32 flat-plate collectors (manufactured by Alternate Energy Technologies), a Superstor Ultra stainless-steel tank (at 80 gallons, it’s a little small, but it’s what I could afford), and an El Sid DC pump from Ivan Labs. Since I installed the equipment myself, it cost significantly less than a professionally installed system.

A Green Building Conference in Montreal

Posted on May 9, 2014 by Martin Holladay, GBA Advisor

Although I live in the middle of nowhere, in the woods of the Northeast Kingdom of Vermont, my house is only a two-and-a-half-hour drive from the cosmopolitan city of Montreal, Quebec. A few weeks ago I made the drive north to meet a few green builders from Quebec and to attend a green building conference called Ecohabitation 2014.

Montreal is a fun city where it's easy to buy a decent baguette. The city also offers the chance to sample delicious food prepared by Quebecois born in Lebanon, Tunisia, Mexico, India, and many other countries.

WUFI Is Driving Me Crazy

Posted on May 2, 2014 by Martin Holladay, GBA Advisor

Is it possible to describe all of the factors that influence heat and moisture movement through a wall during a single day? Perhaps. We could start by listing the outdoor conditions, including air temperature, relative humidity, wind speed, wind direction, the angle of the sun with respect to the wall (its altitude and azimuth), the cloud thickness, the precipitation rate, and the depth of snow on the ground. Needless to say, many of these factors change from minute to minute.

Does a Home with an HRV Also Need Bath Fans?

Posted on April 25, 2014 by Martin Holladay, GBA Advisor

A balanced ventilationMechanical ventilation system in which separate, balanced fans exhaust stale indoor air and bring in fresh outdoor air in equal amounts; often includes heat recovery or heat and moisture recovery (see heat-recovery ventilator and energy-recovery ventilator). system — for example, a system with a 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 an 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.) — exhausts stale air from some rooms in a building, while simultaneously introducing fresh outdoor air to other rooms. The best balanced ventilation systems use dedicated ventilation ductwork. Usually, these systems pull exhaust air from damp, smelly rooms — bathrooms and laundry rooms — and introduce fresh air to the rooms where people spend most of their time — bedrooms and the living room.

All About Radiant Floors

Posted on April 18, 2014 by Martin Holladay, GBA Advisor

So-called radiant floors have an excellent reputation. Many customers report that this type of heating system is comfortable and quiet. Moreover, some suppliers of radiant floor materials and equipment claim that these systems can save energy.

In spite of the purported benefits of this type of heating system, few green homes include a radiant floor heating system. This article will explore why.

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