Green Solar Cafe – renewable energy and green construction

In October 2009, the National Mall in Washington, DC will be turned into a “Solar Village”, where 20 contemporary solar homes from all over US (and one solar home from Germany), will be on display to demonstrated all the latest and greatest in green construction, and renewable energy. This is the Solar Decathlon 2009, a bi-annual event sponsored by US Department of Energy, many colleges and universities as well as private businesses specializing in green buildings.

In 2007 Solar Decathlon, Boston was represented by a Solar Home built by MIT team and many volunteers interested in green technologies. This year it is Boston Architecture College and Tufts University that sponsor the solar home built by Team Boston. Why team Boston? Because many folks that participated in 2007 Solar Decathlon are doing it again.

We and IB Roof Systems (the manufacturer of Cool PVC flat roofing membrane) had our own humble involvement by sponsoring the roof installation on top of this amazing creation of latest architectural designs and green construction technologies. Now, with a new IB 50-mil PVC membrane, this solar home will be completely water-tight and the built in water collection system will provide it with as much H2O as it need. The roof is also very well insulated with over 5 inches if rigid ISO tapered insulation and additional 12 inches of insulation between the rafters. The cool roofing properties of IB Roofs will minimize its cooling needs, and will waterproof the entire building. Hopefully everyone will be eventually replacing their old black roof with a cool roof such as IB, and when roof removal is required by code, calling a skip hire to remove the old material, and then installing these new highly efficient roof is economical and sustainable way to deal with roof tear-off. In some cases the old asphalt roof can be recycled and used in synthetic roofing products.

About the Team Boston Solar Home:

By definition, a solar decathlon project will use different solar technologies available on the market. Team Boston has created such a design where virtually every solar system will be utilized. There will be a 4.6 KW Solar PV system consisting of 20 SunTech PV panels. There will be a large solar hot water installation using Viessmann Solar Thermal hot water panels and water storage unit. But aside from these common, roof mounted solar systems, there will be a new solar thermal system, that will provide up to 70% of FREE heating to this house. It is a so called “trombe wall”. I’ve discussed it in our previous article about solar thermal mass windows. But this time, the Boston Solar Home will have ne and improves solar thermal windows: these are not the old 2×2′ window blocks. It will be a full size 8×2 wall/window units, covering entire south side of this solar house, to provide it with all the heat it will need in the winter. To avoid overheating in the summer, the roof will overhang the southern side by 3 feet, and an additional retractable awning will roll out to provide the shade for these thermals walls / windows.

The walls of this solar house have 2 inches of ISO insulation on the outside and 6 inches of between studs insulation. In total there will be more than 30-r in the walls. Although this is a stick construction home, it can easily be labeled as super-insulated, and it will have minimal heat loss, while providing more than enough energy to be completely off the greed, and won’t need any outside energy sources for either heating or cooling.

Portable design of this Solar Home:

For the competition purpose, the house has to be transportable, therefore it is designed and built in 3 sections on a portable foundation blocks so that it can be put on that flat-bed trucks and transported to DC, for the competition, and then transported back.

The house is designed to be easily taken apart put back together: All the mechanical components, a bathroom, kitchen, heating and air-conditioning equipment and electrical panel ate located in one part, and special quick connect ports are used when two living sections are connected. Solar PV panels and solar thermal system are installed on removable racking systems that are mounted to the parapet walls on the roof, eliminating any roof penetrations and potential roof leaks. This also allows for easy removal and re-installation of both types of solar systems.

There will be a fold-able / removable deck / patio area with a handicapped access ramp, making this home a perfect choice for comfortable living in the summer and winter, and usable by anyone.

Final thoughts about the solar house:

Since this solar home is still in construction stage and many systems are not installed yet, it is difficult to get a complete picture of how it will perform. Still, this will be a true zero-energy home, and will actually produce a lot of excess electric power to be sent back into the grid. My biggest personal concern about this home is the cost: without having exact information and costs run down, the estimates are around $800,000. This amounts to about $1000 per square foot of living space (a maximum of 800 sq. ft. of living space is one of the guidelines of the Solar Decathlon competition), which is very expensive and is not very practical. However this is just  prototype and if it was a mass production home, the actual cost would be a lot less. This cost also includes the transportation to and from competition site in Washington DC, and nominal expenses such as marketing, promotion, creation of the website, etc. So actual construction costs are somewhere about $500,000-600,000.

This is just a firs report on this solar home, and there will be more, as construction goes on. Stay tuned for a complete report on the roof and solar PV system installation as well as overview of the new solar thermal window units.

Useful resources:

http://www.coolflatroof.com/flat-roofing-blog – Learn about the green cool PVC roofing systems, solar roof products and metal roof installation methods.

http://www.mbmcarpentry.com – Green construction and home improvement ins South-Eastern Massachusetts and Rhode Island.

MA Metal Roofing – Flat roofs will not always fit the design of a solar home, and that is where the greenest roofing technology – a Metal Roof – is perfect fit for any sloped roof design.

Although winter is finally over, it is still somewhat cold outside and we have to turn on the heat. Recently I’ve found a very interesting product which can be used by anyone to heat their home or apartment for free. Even if you rent, you can do it without getting the land lord involved. The only things you’ll need are the south-facing windows and a thermal mass solar window.

As you can see from the image above this windows measure 72 degrees F, while outside temperature that day was 22 degrees, with a 27 F high. (Historic weather data).

The 50 degree difference in temperature is the free heat that enter your home and stays. Here is how the Solar Thermal Mass windows work: In a nut shell, it as a 2 inches thick air and water-tight container filled with special liquid that collects and stores solar thermal energy. Special chemicals added tho the liquid prevent stain deposits on the inner walls if the unit. In the picture above, these units are used a building blocks, and cover almost a half of the south-facing wall.

In the winter, when the sun is low, these solar thermal mass windows collect solar heat since the sun hits them directly. In the summer, sun is much higher and with appropriate shading, these thermal mass windows keep home well insulated without collecting any heat. Additionally, a special low emittence and high solar gain, argon filled window unit is installed just outside the thermal windows, so they are not directly exposed to the outside temperature.

How to heat your existing how for free

The picture above was taken in a new construction house, but for most people the interesting question is how to use these thermal mass windows in the existing home or apartment?

My plan was simple: I have 6 large windows that face south and an unheated balcony which cannot be used in the winter because it is too cold there. In the heated living space, we have new double pane Low-E windows installed which are much more efficient than the original single-pane wood windows from the 50′s. I am going to build an enclosure in which I can stack 4-6 thermal mass solar window units, and have them up in the window during the winter months, and take them out in the summer.

This won’t be as efficient as the one in  the new construction home above but it will certainly help reduce my heating bill and carbon footprint.

As for the balcony, I first need to replace all the single-pane glazing and then I can stack the thermal mass windows all along the bottom if the windows. I’ll build special shelves to make the process of putting them up for the winter and removing them in the summer, easy.

Resources:

Find more green construction ideas at Green Home Ideas blog.

More green blogs at Home Blog Directory