Hope you can make it to the next B-Green talk I’m organizing. Reserve your tickets here.
When it comes to renovating for energy efficiency, home energy auditors are always stressing the importance of starting with the “low-hanging fruit,” measures like air sealing that are relatively cheap but pay big dividends in energy savings. Equally important is making sure you’re taking advantage of any rebates or incentives available in your area. I wrote a quick roundup of programs in the Seattle area, published in this month’s Natural Awakenings magazine. You might be surprised by how much you can save!
The article starts on p. 23 of the online edition.
Earth Techling and Fine Homebuilding Magazine just published some interesting articles about our house that highlighted the relatively low cost-per-square foot price tag. It’s great to see the idea of affordable net-zero building getting some media attention. Even more gratifying, however, is that I talked to the builder of our house, Ted Clifton of TC Legend Homes, and he says that he gets a call about every week from someone who has heard of our house and is interested in building a zero-energy house of their own.
It’s no wonder people in Seattle and elsewhere are interested in this type of construction, since it represents some serious long-term savings. One commentator on the Fine Homebuilding article wrote:
Of course, for a net zero house any initial savings is really just icing on the cake anyway… Can you imagine the savings that will take place during the life-span of the home? . . . My average cost for gas alone is $1,500/yr. (hot water & furnace), literally burned every year (“litterly” was my Freudian slip). If you include the cost of electricity, then I’m out another $950/yr., for a total expense of $2,450/yr. (gas & electrical alone – my water & sewer are another “drain” altogether 🙂
So, every ten years I’m out +/- $24,000, which coincidently adds up to about the same as my 2 latte/day addiction… Maybe that’s the way to market this to the Seattle-area crowd: net-zero = free caffine 🙂
Here are the articles . . .
Earth Techling: Attractive Net-Zero-Energy House on a Budget
Fine Homebuilding: Seattle Homeowners Build an Affordable Net-Zero-Energy House
If the average human takes about 20,000 breaths per day, and Alex and I are home about half the day on average, that means we fill our house with about 600,000 exhalations per month. Add those of our new puppy, Beatrice, whose main activity is to sit around and breathe 23 hours a day (and run around like an insane monkey the other hour), and you start to approach a million breaths.
That’s a lot of hot, humid air. Where does it all go?
Researchers from Washington State University have chosen our house for a study that will determine just that.
They’re placing sensors in about fifty Puget Sound houses to monitor key air quality indicators. Their equipment also tracks when ventilation fans are on and when doors are open. The goal is to find out how ventilation works in today’s newer, more airtight homes.
Poor air quality can cause tiredness, the inability to concentrate and make decisions, and even serious illness. Avoiding products that emit harmful pollutants into the air is important, but to ensure that your indoor air quality is healthy, ventilation is required.
What’s Being Tested
Air quality professionals can measure a range of factors, including mold spores and volatile organic compounds (VOCs), but this study focuses on one of the best and simplest indicators: carbon dioxide (CO2).
We exhale CO2 with each breath, and levels rise if ventilation is insufficient. CO2 itself is not toxic, but high concentrations, above about 1,000 parts per million, indicate that a room may be under-ventilated and could be harboring other, more toxic compounds.
Getting Ventilation Right
Testing your air can help you save energy. High levels of CO2 indicate that you may need to increase your ventilation, but unusually low CO2 levels may tell you that you can cut back. Over-ventilating your house can’t harm you, but it may be wasting energy by allowing too much conditioned air to escape, undermining the effects of good insulation and an air-tight building envelope.
I’d love to get a controller for our ventilation fan that turns it on when a certain CO2 level is reached. Unfortunately, the cost is prohibitive.
Representatives from WSU have asked us not to share any results until the study is complete, but that doesn’t stop me from checking the displays on the little meters they’ve placed throughout our home. It’s very interesting to see how CO2 goes up when a door is closed and our ventilation system is turned off (one of the scenarios they’re testing).
What I can say now is that we have a very tight house, and the difference between ventilating and not ventilating is fairly dramatic. One thing is for sure, our houseplants are happy: When CO2 rises, they start growing! In fact, if you ever notice your indoor air feeling a bit stuffy and your plants growing like mad, it may be a sign that you should test your air.
John Brooks, a reader of my recent article in Green Building Advisor asked this:
You posted the Net Energy Balance for 12 months. I am curious how that relates to your actual Energy Bill….the sum of the checks that you write to the “power provider” over 12 months? (Including the base customer charge and difference in buy-back rates)
That’s a good question that others have brought up to us before. The short answer is that during the cold, dark days of our first winter, we paid small electrical bills. In the spring, when the sun came out and our heating needs diminished, we started generating more power than we were using, which showed up as credits on our electric bill.
After about fifteen months of living in the house, we currently have a credit of about $230 on our account. We had the option of requesting a check, but we decided to leave that credit on the books to pay our bills this winter. If our usage is like last year, that $230 credit should more than last us through the winter, so we probably won’t be paying anything out of pocket from now on.
Here’s a breakdown of our last twelve months of bills:
10/28/11 - 1/13/12: $90.01
1/13/12 - 03/14/12: $55.42
3/14/12 - 5/11/12: -$32.25 (credit)
5/11/12 - 7/11/12: -$125.07 (credit)
7/11/12 - 9/11/12: -$92.98 (credit)
9/11/12 - 11/9: -$12.29 (credit)
The housing bubble had burst, the banks weren’t lending, and we were newlyweds who had no business even thinking about building a custom home, let alone Seattle’s first net-zero house.
Read the article I wrote for Green Building Advisor.
Our builder, Ted Clifton, just finished his latest house in Leavenworth, WA. We were disappointed that we had to miss the housewarming party, but from the photos, it looks really cool.
Unlike our net-zero-energy house, this new one follows the stringent Passive House standard, developed in Europe.
The hallmarks of a Passive House are super-high levels of insulation, a design that takes advantage of passive solar gain, and, as a result, has little need for heating beyond that provided by the sun, warm bodies, and appliances. Passive Houses also come with a list of requirements, like a heat recovery ventilator, a somewhat costly piece of equipment that recoups some of the energy that would normally be lost from circulating fresh air through the house.
Are Passive Houses better than net-zero houses? It depends who you ask.
We opted for the net-zero approach because producing as much energy as we used over the course of a year was our first priority. Passive Houses can be net-zero, too, but it’s not required by the standard, and it adds to the building costs.
The focus of Passive House design is to reduce the amount of energy required to heat and cool the house (by up to 90%), whereas the focus of a net-zero house is to offset 100% of the power required to heat, cool, light, and run the home. In any given moment, a net-zero house like ours might be using slightly more power than a similarly sized Passive House, but it would make it all back from its solar panels over the course of a year.
Passive Houses tend to cost more to build since they have even more insulation than a typical net-zero house. Critics of the PH standard point to diminishing returns. To chase after that last little bit of air tightness and insulation to bring a house up to the Passive House standard can be expensive, and, in many cases, the potential energy savings could be easily and much more cheaply attained by adding a few solar panels.
On the other hand, Passive Houses are elegant in the simplicity of their mechanical systems. Some of them require so little auxiliary heat that they can be warmed solely by a cheap little wall-mounted electrical heater, eliminating the need for costly heating systems. Proponents of Passive Houses point to the fact that mechanical systems eventually wear out and solar panels stop producing as much power over time, while a well-built, well-maintained house can last hundreds of years.
During our first winter in our house, we spent a lot of time tweaking the radiant heat system, and our heat pump required a replacement electrical board (under warranty, but still a hassle). The reality is, however, that many Passive Houses, especially larger ones in colder climates, also make use of heat pumps. And, if you’re interested in achieving net-zero-energy, you’ll need to install solar panels and an inverter on your Passive House.
Looking back on it, we wouldn’t have turned down the extra insulation the Passive House standard calls for, but not if it had required us to have smaller windows or forgo our net-zero-energy goal. By not strictly limiting ourselves to the rigid standard, we were able to achieve net-zero much cheaper.
Either way, both types of house save lots of energy, and I’m happy to see them being built. Plus, Ted’s newest project is just plain cool. Check out the sliced-off boulder table in the middle of the room!
Know anyone who wants to have a zero-energy holiday? Have family visiting Seattle who need a place to stay? Our house is now available on Airbnb for $150/night.