Friday, April 29, 2011

Home Energy Saver a big "heat" among student renters, parents, even grandparents

We have several programs for teaching home energy analysis here at Unity College. We teach a basic course in energy efficiency to all Sustainable Design and Technology and Sustainable Energy majors. Students get experience working in the Unity town energy program, Energizing a Community.

There also are two local Building Performance Institute classes to which students are directed to become externally certified Home Energy Auditors (one run by our friend George Callas at Newforest Institute at Brooks, Maine, the other run by our Rocky Mountain Institute Fellow Anne Stephenson at USM.)

But these are programs for future professionals. What about programming for ordinary folk?

Well, in our general education Interdisciplinary Core III class, Environmental Sustainability, which I teach each year to between 100 and 125 students, there's a basic introduction to the ideas of home energy auditing, and students can also choose to satisfy the quantitative analysis homework assignment by completing the Lawrence Berkeley Laboratory's quite excellent Home Energy Saver online.

The Home Energy Saver is a more-or-less full service energy audit program provided online using interactive web-based systems. It contains a geographically accurate building energy model as well as an embedded spreadsheet for electricity and fuel consumption.

The program gets the outdoor design dry bulb temperature from your zip code. You also plug in specifics for the insulation values of walls and ceiling, the shape of the building, and the heat sources. It then calculates the home's heat load, and compares that to the actual fuels usage. It gives you options for home improvements that will save money, many of which are eligible for the 30% home energy tax break.

It also looks at your appliances and lighting.

Students generally prefer the Home Energy Saver homework to the other way they can satisfy the quantitative analysis requirement, which is to solve some kind of (very basic) dynamic systems problem in population, climate, or energy using pen-and-paper difference tables, MS Excel or the Stella ecological modeling software package.

(Because this is a general education class, students come to it with a very wide variety of mathematics background, and so it's necessary to have a very wide range of assignments so students can self-place into more difficult or useful ones as they see fit.)

Students are required to provide a narrative with their Home Energy Saver results. Here's a testimonial from one of our current students supplied as part of his narrative:

"My grandparents were very surprised to see how much money they could save by just doing a few simple upgrades to their home. Since I presented the results of this Home Energy Saver to them, they have traded in most of their large appliances, including their refrigerator, washer/dryer, and dishwasher for Energy Star performance products. They have also changed all of their lighting to CFL bulbs. My grandfather also just had his old oil furnace replaced with what I think he called a "System 2000." He told me it is really quiet and saves him significant fuel costs."

Pretty useful, I'd say.

Looking at the numbers, this particular set of grandparents must have had their old appliances a long time, which is not that unusual. New Englanders don't like to spend money on new things if they don't have to.

But the older appliances, especially older furnaces and fridges pre- 1980, may use so much excess energy, the new more efficient ones can easily pay for themselves in a few years.

Here's another:

“I found that our existing home energy costs totaled approximately [sic] $7,052, and that with some suggested upgrades we could bring that down to $4,288. I found the breakdown of energy savings to be the most interesting portion. For heating the cost went from $5,123 to $2,900, hot water went from $1,050 to $582 and lighting went from $87 to $31. I know for a fact that there are things that could be improved upon that I don’t believe are well-reflected in the overview, including things such as upgrading from our 1990s washing machine and dryer to a set-up that is Energy Star rated, along with the refrigerator and stove. However, being tenants and college students, this is not something we can efficiently upgrade.”

I'm not sure how much our local landlords appreciate our students ability to fathom the inefficiency of student rentals using the HES. I expect it's caused a few heated student-landlord discussions. It's very easy for landlords to pass on high energy costs to renters. I've personally audited one or two of these places, and have the HES results for many more, and quite a few of them are just holes in the environment into which students sink money they don't have. One set of roommates this year discovered they were spending $5,000 annually on heat alone!

The college would prefer to house as many students as possible on-campus, either in the older energy efficient dorms like Maplewood or Cianchette, or the new Terra Haus passive solar-type dorms, of which we expect to build quite a few more in coming years. If students want the roommate-house experience, they can have it in college-supplied cottage-style housing, where we can ensure we're not destroying the planet's climate just to heat a building.

The HES results in the image above aren't from this particular student's homework. Privacy rules wouldn't allow me to show you those results. Instead, they're from the Womerlippi Farmhouse. There, after years of plugging away, the scope for energy savings is not so great, so the image is not the best illustration of how the system works. The results show only a small potential, in our hot water system, and in the two fridges and two freezers we run (to store all that farm produce). The Home Energy Saver says I can get my hot water expenses down to only $4/year from the current $600 or so if I switch to solar hot water. And one day we might get a largere freezer and retire both of our smaller models. We also use a little electricity for heat, about $200/year.

But click on the image to enlarge it, and study the histogram. The proposed hot water savings are obvious. The system would cost me around $3,000 if I installed it myself. However, this is not the way I'm going to do things: I like to prioritize. I have about the same dollar amount of insulation left to do first, to eliminate roughly half or the remaining heat costs. This is not cost effective insulation based on payback, but it will make the house more comfortable.

I actually don't believe the four dollar solar hot water number because you generally can't make very much solar hot water in a Maine winter. I think the $3,000 system will only save me $400 a year. But still, that's a pretty good return on investment.

Therein lies a good lesson:

As with all "black box" calculations systems, there remain inaccuracies with the HES, and it's far better for professionals to be able to construct their own models from basic principles.

A "black box" is my name for a modeling system where you can't see "the works". You plug in numbers and the box spits out a number, but you can't see why.

The Home Energy Saver, despite being an awesome tool, is one such black box.

This is actually one reason I think our energy efficiency class is superior in many ways to the proprietary programs that are out there. We teach building energy models from scratch.

But for the average Jill or Joe, the HES can save a lot of money and pollution, and it's completely free.

Why not give it a try?

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