Pushing the Envelope

(In order to appreciate the events from this past weekend, the reader will want to remember that our straw bale home is currently heated by our backup system, a radiant floor fueled by propane. It's a great incentive to complete our Finnish masonry heater this summer for use in Winter 2010-2011.)

It was inadvertent that we were able to test the passive solar and insulative values of our home last weekend. We really meant to order the propane last week. Really. But it's getting to be good maple weather, which means busy times at home and work.

So we called for propane on Saturday. Sure, they'd be willing to deliver, for an extra $150.00.

Ah. Okay then.

So Saturday began with a feeling of regret that quickly turned into opportunity. As I've mentioned before, the insulation value of the walls of our home is quite high compared to conventional construction. We've created an efficient "envelope" (highly insulated walls, floors, ceilings, windows & doors.) We have a nice amount of passive solar gain through our south-facing windows and a decent amount of thermal mass in the floor. (In layman's terms, thermal mass refers to the ability of a material to absorb heat, to be radiated out over time.) But here's the thing---even though we theoretically knew the insulative value of our home, we had never tested it directly by turning our heat off---until this weekend.

By Saturday morning, we knew we needed to get through two days without using much propane, so we turned the radiant floor system off. (The radiant system works through a thermostat that measures the floor temperature and uses hot water---heated by propane---to keep the floor a constant temperature. The heat from the floor radiates upward and heats everything in its path.) The nice thing is, we can adjust the thermostat to decrease the temperature of the floor, but it also has a switch by which we can simply turn it off.

Looking back, I wish I had treated this weekend more scientifically and taken air and floor temperatures each hour. But anecdotally, here's what happened: we had typical maple weather all weekend, so outdoor temperatures climbed to around 45 degrees F during the day and dipped below freezing at night for both Saturday and Sunday. Each day, the passive solar energy raised Haven's interior temperature to around 69 degrees. Overnight, the air temperature in our home came down to around 64 degrees.

Overall, we were extremely pleased with how we fared at Haven this weekend. There were a lot of variables at play, such as the fairly pleasant March weather with sunshine. (Certainly, if we hadn't had sun, the house wouldn't have been as warm each day.)

So what are the potential implications of our inadvertent experiment? My conclusion is that since I am home during the day, I'll be able to monitor the outside weather and adjust the thermostat on our radiant system accordingly to greatly reduce our demand for propane on sunny days. It makes me think back to a Cape Cod we used to own, to times when we considered ourselves lucky to be able to turn the furnace off toward the end of April. What a great opportunity to be able to reduce our fuel use a month and a half earlier! It also brought me back to our time at Terra Dei, learning to build smaller fires each day as Spring progressed, so as not to waste wood and overheat the house.  It reminded me that life it built on a learning curve.

The owner of the propane company personally made our delivery yesterday. Having helped Fred choose the size and site of the tank for our proposed radiant heating system, he was curious as to how we made out this winter. I described how pleasant the floor was to walk on, then related our "experiment" from turning the system off this past weekend. He smiled ruefully, saying, "Well that's great for you, but not good news for me!" Though I kept quiet, I was dying to say, "Just wait until our masonry heater is in place next year!"

Instead, I chose to smile and wish him a good day.

Thanks for joining me along our journey!
Grace
xxoo

7 Reasons to Choose a Blue Roof

The blue steel roof is one of the visually distinctive features of our home. Although beautiful, it was initially chosen for function. Here are seven reasons to invest in a steel roof.

Steel panels are...

1. Long Lasting
Galvalume* panels boast a 25-year warranty, with a 30-year warranty against chalk and fade of the color of your choice. Panels are available in 18 different colors.

2. Fireproof
Steel panels are noncombustible.

3. Waterproof
Steel is impervious to water. Snow and ice are shed in the winter.

4. Recyclable
The panels are made of 25% recycled steel and are recyclable.

5. Quiet
Contrary to popular belief, steel panels provide a quiet roof. The mental image of rain drumming on a metal roof comes from barn roofing, where the noise originates from open framing and no insulation.

6. Affordable
Although a steel roof may initially cost more, costs are lower over the life cycle of the roof.

7. Ideal for Rainwater Collection
Haven was designed around a system of cistern tanks that serve as our sole water supply. According to Suzy Banks and Richard Heinichen, the best roofs for rainwater collection are metal (16).

We chose to purchase the Galvalume* steel panels and construction supplies from American Building Components. (*Galvalume is the trademark name of the coating applied to their bare sheet steel products.)

Readers who have been with me from day one know why our roof is blue. Fred and I traveled to the Big Island of Hawaii in July, 2005. Many of the homes there have metal roofing in a variety of colors. The color that I identify most with Hawaii is a tranquil blue. While I knew it would be an impossibility to transplant my life to Hawaii, choosing a blue metal roof for my new home was my way of acknowledging my inner wish to live the rest of my life out at South Point on the Big Island.

Are you curious as to what the runner-up color choices were? I thought so!
Life Under an Ivy Green Roof
Life Under a Burnished Slate Roof
Life Under a Burgundy Roof
Life Under a Koko Brown Roof

Koko Brown? Yeah... I've put up with too much brown in my life. For me, I'm happy to write from under my blue roof.

xxoo





American Building Components
www.abcmetalroofing.com

Banks, Susan and Richard Heinichen. Rainwater Collection For the Mechanically Challenged. Texas: Tank Town, 2004.

Living the Radiant Life

Living in a straw bale house, we get a lot of questions. These range from the comical "Three Pigs" type allusions, to the more serious, "Isn't it a fire hazard to have straw in your walls?" Once people realize that the straw serves as insulation, they want to know how warm the house is. As in all the homes we've lived we keep the temperature around 68 degrees Fahrenheit. We could certainly keep it warmer, but we try to treat heat as the valuable resource it is. Hence my ever-growing collection of wool cardigans.

When people ask how warm our house is, I think what they really want to know is how much energy we are saving. Until we've lived here a year we won't have a definitive answer to that. According to Chris Magwood in his book Straw Bale Building, "Insulation values (commonly referred to as R-values) for conventional residential wall systems typically range between R-12 and R-20, depending on climactic conditions. Straw bale walls have R-values between R-35-R-50, depending on their width." In that way, using straw bales for insulation has allowed us to significantly reduce the amount of energy required to heat and cool a house this size.

Haven Homestead is designed to operate on two heating sources. The first is a radiant floor system, fueled by propane. The second is a woodburning Finnish masonry heater. These two heat sources will work together in the future; the masonry heater is not yet online. We look forward to firing it up next winter, fueling it with wood split from our homestead. This will allow us to dramatically reduce our reliance on propane.

There are many positive aspects of living with a radiant floor. Extremely quiet systems, we don't hear the rush of the furnace turning on, the drone of air whooshing through a register. Gone are the days of itchy skin and nosebleeds from air that is overdried from a forced air system. Radiant systems are also hidden from sight in the subfloor; not only visually pleasing, this also makes them extremely childproof. They aren't prone to large fluctuations in temperature and distribute heat evenly.

For those of you who may have never experienced a radiant floor, ours is an open direct system designed with components from the Radiantec company based in Vermont. "The system uses one very efficient water heater to make domestic hot water for the home and warm water for radiant heating. Radiant heating systems warm the building by locating heating tubes within a large surface area of the building and then circulating warm water through the tubes." (Radiantec Open Direct System Installation, pg. 1) When the construction of the masonry heater is complete the two systems will work in concert, with heating coils for the floor running through the fireplace. This will preheat the water before it arrives at the hot water tank, reducing the amount of heat needed (and the amount of propane used) to bring the water in the hot water tank up to the desired temperature.

Two of the largest advantages for us in choosing a radiant floor heating system were ease of installation and system cost. According to the brochure we obtained from Radiantec, "Installation of radiant heat does not have to be hard, and it does not have to be expensive." They go on to say, "Radiantec Company thinks that the task of installing underfloor radiant heat is the task of a reasonably competent handyman...and that the work can be done with common, readily available tools." I would consider their opinion correct on both counts. Though we did have a licensed plumber help install the hot water manifold, Todd and my father were able to complete the actual installation of the floor elements. Radiantec designed the layout; we placed strapping across the entire subfloor and laid the Pex tubing between the strapping members. We filled the cavities next to the Pex tubing with sand. (Sand was chosen for its excellent heat retention and relatively low cost, as well as the fact that it requires no additional manufacturing, as is the case with cement.) We covered the entire first floor with cement backer board and laid ceramic tile wall-to-wall.

Regarding system cost, our expense for purchasing the components of the system (Pex tubing, manifold, reflective barrier, couplings, pump, all valves, digital temperature display, pressure gauges, etc.) ran around $2,400. An additional $1,696 was needed to purchase the hot water tank, bringing the total component cost to $4,096. (Note, in an effort to save in construction costs, we opted for a less expensive water heater than the extremely efficient Polaris recommended by Radiantec, with the intent to replace it with a Polaris in the future.) At the time we purchased the materials for our system a comparable conventional baseboard hot water system would have cost us approximately $6,500 (Radiantec Heating Systems, pg. 3).

Although it was not my intent to turn this post into an advertisement for Radiantec, we've been very pleased with our team effort to design and install Haven's radiant floor. Radiantec is a member of the International Code Council. They offer assistance designing systems, help with materials specification, and provide detailed installation manuals. They also provide unlimited toll-free technical support for as long as you own your system. Our house is warm and draft-free. As our son is often wont to do, you can walk across the ceramic tile in your bare feet in winter with a level of comfort.


Taken just this morning, featuring Batman pajamas and bare feet.

Resources:

Magwood, Chris and Peter Mack. Straw Bale Building: How to Plan, Design and Build With Straw. Gabriola Island: New Society Publishers, 2002.

Radiantec Incorporated
Box 1111, Lyndonville, Vt 05851
(800) 451-7593
FAX (802) 626-8045
www.radiantec.com