Musings of an Energy Nerd

Air-to-Water Heat Pumps

Posted on January 8, 2016 by Martin Holladay, GBA Advisor

Most air conditioners and heat pumps sold in the U.S. — including most split-system air conditioners and ductless minisplits — are air-to-air heat pumps. During the winter, these appliances extract heat from the outdoor air and deliver warm air to a house through ducts or small fan-coil units. During the summer, these appliances deliver cool air to a house and dump unwanted heat into the outdoor air.

GBA Prime Sneak Peek: Green Building in the Cheap Energy Era

Posted on January 5, 2016 by Martin Holladay, GBA Advisor

GBAGreenBuildingAdvisor.com Prime subscribers have access to many articles that aren't accessible to non-subscribers, including Martin Holladay's weekly blog series, “Musings of an Energy Nerd.” To whet the appetite of non-subscribers, we occasionally offer non-subscribers access to a “GBA Prime Sneak Peek” article like this one.

Green Building in the Cheap Energy Era

Posted on January 1, 2016 by Martin Holladay, GBA Advisor

Homeowners’ interest in energy efficiency measures waxes and wanes. During the 1970s, when oil prices repeatedly spiked upwards, everyone wanted to save energy. However, in the 1980s, when oil prices collapsed, Americans forgot about saving energy, and most of us reverted to our usual wasteful habits.

By 2008, oil prices were high again, and green builders were receiving lots of phone calls from homeowners who wanted lower energy bills. But between June 2014 and now, oil prices have collapsed again, tumbling from $115 to between $37 and $40 a barrel. This raises several questions:

Climate Affects Home Design

Posted on December 25, 2015 by Martin Holladay, GBA Advisor

If you go to one of the many web sites that sell house plans, you can use filtering software to sort through hundreds of available plans by a variety of criteria: square feet, number of bedrooms, number of bathrooms, number of stories, or even “number of garage bays.”

On most of these sites, however, you can’t sort by climate zone. Why? Because most house plan companies ignore climate. They’re happy to sell customers in Minnesota the same house plan that they sell customers in Florida.

Insulating a Cape Cod House

Posted on December 11, 2015 by Martin Holladay, GBA Advisor

If you own an older Cape Cod home, you have my sympathy. If you’re the type of homeowner who regularly tackles DIY projects, you’ve probably spent weeks chasing air leaks with a foam gun, lying on your back in a cramped attic. And there's a good chance that, in spite of your efforts, your house still suffers from ice dams.

I’m sorry for your troubles. You deserve better.

If you are thinking of building a new Cape, it’s not too late to get the details right — as long as you’re still at the planning stage.

Flashing Brick Veneer

Posted on December 4, 2015 by Martin Holladay, GBA Advisor

Residential construction practices in the U.S. have a certain Wild West flavor. Quality standards vary widely from one area of the country to another. For example, while builders in some regions pay meticulous attention when lapping a water-resistant barrier (WRB) or installing wall flashing, builders in other regions ignore best practice recommendations and code requirements.

Making Room for a PV Array

Posted on November 27, 2015 by Martin Holladay, GBA Advisor

Compared to a photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. system, a solar hot water system yields very little energy per dollar invested. I presented that argument in a 2012 article called “Solar Thermal Is Dead.” Two years later, in 2014, an economic comparison between these two solar technologies showed a stronger tilt than ever before in favor of PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow., leading me to write a follow-up article called “Solar Thermal Is Really, Really Dead.”

Wall Sheathing Options

Posted on November 20, 2015 by Martin Holladay, GBA Advisor

For the past 30 years, the majority of new homes in the U.S. have been built with wood-framed walls sheathed with oriented strand board (OSB). Most builders are so comfortable with OSB wall 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. that they never consider using an alternative material.

In fact, a wide range of materials can be used to sheathe a wood-framed wall. In addition to OSB, builders can choose plywood, fiberboard, rigid foam, diagonal boards, and fiberglass-faced gypsum panels. If you’re a dyed-in-the-wool OSB user, it might be time to consider some of the available alternatives to OSB.

Where Does the Air Come From?

Posted on November 13, 2015 by Martin Holladay, GBA Advisor

Most American homes have a bewildering array of diffusers, registers, and grilles that blow air out or suck air in. For many homeowners, these apertures are somewhat mysterious. We all know that there must be a duct behind each grille, but where does the duct lead?

Another North American Magic Box

Posted on November 6, 2015 by Martin Holladay, GBA Advisor

Over the past few years, GBAGreenBuildingAdvisor.com has published several articles on “magic boxes” — a type of combination appliance that functions as a ventilation system, heating system, and cooling system. Most recently, I wrote about the CERV, a magic box manufactured in Illinois. Now a Canadian manufacturer has come out with a magic box that resembles the CERV.

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