Guest Blogs

Passivhaus versus Net-Zero Energy Buildings

Posted on December 10, 2012 by mike eliason

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. (or nearly zero energy building) vs. net zeroProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. Calculating net-zero energy can be difficult, particularly in grid-tied renewable energy systems, because of transmission losses in power lines and other considerations. debate has become an ongoing discussion that rears its nerdy head every few months. It really first took grasp shortly before Martin Holladay published his Net Zero versus Passivhaus blog. Recently, the topic has made its way into several conversations – and my arguments for nearly-zero-energy buildings (NZEBs) or NZEBs + renewables always spark a lively conversation.

Insulating Stud Cavities in Existing Homes

Posted on December 4, 2012 by Erik North

I was about to launch into an article on insulating empty wall cavities in an older house when I realized that the topic is best broken down into two sections: a survey of the products you can use to insulate your wall cavities, and a discussion of installation techniques and methods. I'm just glad I realized that in the first paragraph as opposed to the fifth page. So this article will focus on insulation materials.

Seeing Red on a Green Property Appraisal — Part 3

Posted on December 3, 2012 by Roger Normand

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the 17th article in a series that will follow their project from planning through construction.]

Getting an appraisal to value green enhancements requires the appraiser to take two actions: (1) To recognize and list the green enhancements on the appraisal form; and (2) To assign a value to these enhancements.

Installing a Photovoltaic System

Posted on November 27, 2012 by Marc Rosenbaum

[Editor's note: What follows is a compilation of blog entries by Marc Rosenbaum describing the performance of the photovoltaic system installed on the roof of his Massachusetts house.]

Seeing Red on a Green Property Appraisal — Part 2

Posted on November 20, 2012 by Roger Normand

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the 16th article in a series that will follow their project from planning through construction.]

If you have read my previous blog (“Seeing Red on a Green Property Appraisal – Part 1”), you know that the appraiser failed to list or value any of the green/energy efficient aspects of EdgewaterHaus. Does it matter?

Absolutely!

Choosing an Efficient Refrigerator

Posted on November 19, 2012 by Marc Rosenbaum

When we moved into our house, it had the original Maytag 18.5-cubic-foot refrigerator that was installed in 2000. It had one feature I had never lived with before: an icemaker.

It took me some time to realize that the weird sounds I occasionally heard coming from the fridge was it cranking out the cubes. We don't use much ice, and being middle-aged actually learned in our youth how to fill ice cube trays (similar to being able to count, and tell time by the big hand and the little hand, and other lost arts), so eventually I turned that feature off.

All About Energy Efficient Mortgages

Posted on November 16, 2012 by Brentt Taylor

A relatively new home financing option — the energy efficient mortgage — can let home buyers qualify for larger loans than they might otherwise, while improving their homes with environmentally friendly, cost-cutting upgrades that can reduce energy bills.

An energy efficient mortgage (EEM) is a great way to help a family improve their home and save money while doing good for the environment, and securing one is a lot simpler than you might think.

Seeing Red on a Green Property Appraisal — Part 1

Posted on November 14, 2012 by Roger Normand

[Editor's note: Roger and Lynn Normand are building a Passivhaus in Maine. This is the 15th article in a series that will follow their project from planning through construction.]

I am seeing “red” on what’s supposed to be a “green” residential property appraisal.

No, I’m not color blind, although my wife Lynn says I am “seriously color challenged” for my occasional fashion faux-pas. Perhaps so.

Shades of Green: the 1970s vs. the Millennial Generation

Posted on November 13, 2012 by Vera Novak

Recently a friend asked for help in designing an off-grid house. Interestingly, I pulled out the old books from the '70s to show as examples and inspiration. We tagged a combination of ideas: an earth berm house, a passive solar house, an attached greenhouse buffer space, a solar thermal system, and a stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season. heating/cooling system incorporating a heat sinkWhere heat is dumped by an air conditioner or by a heat pump used in cooling mode; usually the outdoor air or ground. See air-source heat pump and ground-source heat pump. (southern rock exposure) and a cool northern forest glen.

It all seemed so — natural …

Living With Point-Source Heat

Posted on November 7, 2012 by Marc Rosenbaum

When we yanked the oil boiler, we replaced it with a wall-mounted minisplit 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 the main level open area that includes kitchen, dining, living and our little office area. We closed off the first-floor bedroom and bathroom so those rooms are only heated by conductionMovement of heat through a material as kinetic energy is transferred from molecule to molecule; the handle of an iron skillet on the stove gets hot due to heat conduction. R-value is a measure of resistance to conductive heat flow. and air leakage through the walls, and so they get cold — in the high 40°Fs at the lowest last winter.

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