Energy Calculations

Why we bought a Plug-in Hybrid

Jul 11, 2013

If you remember one of our early solar posts when building the house, we initially assumed that solar was going to be too expensive for us. Then we ran the numbers and found that the rate of return was actually quite attractive over the log run.

It's official, we earned our 5+ Energy Star rating. But the result was not what we expected.

Jan 24, 2012

Our contractor used our house as an opportunity to apply for status as an Energy Star builder. It worked. He’s now an Energy Star approved builder, and we have a 5+ star Energy Star home. In the process we discovered a big difference in the projected energy usage by our Energy Star certified rater using REM/Rate and our certified PassivHaus consultants who used the PassivHaus spreadsheet.

Thousand Home Challenge

Jul 12, 2011

I was reading The Right Target, a post on Marc Rosenbaum’s blog a few weeks ago and realized that we too might be able to qualify for the Thousand Home Challenge.

The Energy Nerd that Kicked the Hornet's Nest

Apr 1, 2011

Martin Holladay is stirring the pot over at GBA. He has posted a piece today entitled, Are Passivhaus Requirements Logical or Arbitrary? While I tend to agree with his points in general, I also agree with many of Mike Eliason’s points in his response, A Passivhaus Rebuttal: In Defense of the Standard.

Solar Power Planning

Mar 7, 2011

To get to net zero energy use, we must produce enough energy to offset our energy usage over a year. We originally planned to live in the house a few years before installing photovoltaic (PV) panels on the roof, but after we ran the numbers we decided it made sense to do it now rather than wait.

The cost of infiltration

Jan 30, 2011

There are several ways to approximate the cost of a leaky house. Before I proceed, however, I just want to mention there are other much larger longterm monetary benefits to building a tight house, like a longer lifecycle and less maintenance due to keeping critters and moisture out of the building enclosure. I’m sure there’s a way to calculate the value of these additional benefits, but it’s beyond my abilities (and you’d have to use a lot of assumptions to get there).

Having gone through the numbers, there is some value to understanding the factors that are used to estimate the cost of infiltration, as well as the proportion of infiltration cost to the overall energy costs required to heat a house.

How tight is tight enough?

Jan 25, 2011

As the snow piles up outside, I have turned my thoughts to Spring. Not only because it’s warmer and nature is waking from it’s long slumber, but also because I hope we will be conducting our first blower door test by then. Specifically I’ve been considering what type of results I should be expecting from the blower door tests, and how to interpret them.

We made the decision early on to build an air tight house. This guided our choice of building materials, Zip system and tape for the exterior sheathing, gaskets and acoustical sealant to seal all other connections, and foam to seal gaps at the rims, windows and doors. The blower door test will help us seal any gaps we missed. But what target should we aim for? How do we know when the house it tight enough?

Final Energy Analysis and Recommendations

Sep 13, 2010

Back in May (see June Updates) we met with the energy guys (DEAP Group). At that time they reviewed the plans at that stage and made recommendations to improve the air sealing and insulation levels.

June Updates

Jun 16, 2010

April Update

Apr 20, 2010

Lots of updates this week. We have updated house plans. We received window estimates. We hired energy consultants and a land surveyor. We have estimates for the driveway and getting electric service to the site. It has been a very busy two weeks.

Infiltration and Ventilation

Feb 15, 2010

Why am I devoting an entire post to the movement of air you ask? And why now, at the early design stage?

Favorite Building Sites and Books

Feb 11, 2010

Just thought I’d share a few of the sites, links and books that I’ve been using a lot these days.