So I’ll let the big guys do their things, while I tell you about the event, which so many people waited 2+ years for, and worked so hard to make it happen – ladies and gentlemen – Solar Decathlon 2009!

This was our first Solar Decathlon, but certainly not the last. Since we were sponsors of Team Boston Solar Home, most of my coverage will be focused on it. However, there were many great solar homes this year: Team California and Team Germany were battling for first place (you can see Team Germany solar home in the picture above – a black house, second from the right).

As I wondered through the Mall, looking at these homes and being hesitant to stand in line to see very similar interior set-ups, my main focus was on the outside. Solar technologies, energy efficiency and exterior design were my main concern, as these factors make a true solar home, while the inside can always be remodeled.

Team Boston Solar Home:

As a future architecture student, and a “construction worker” now, I look at these houses with a slightly different perspective than most people. For me, the ease of construction, most energy efficiency and reasonable cost are the most important things, followed by a nice design. Unfortunately, many of the innovative approaches used for this competition, are not accessible to the masses, and remain to be a privilege for the most extravagant home buyers with deep pockets. While I have no problem with it in general, in my opinion, the purpose of a Solar Decathlon is to move innovative green building technologies into the mass housing market, so that such technologies would actually make a major difference in improving the environment and reducing CO2 emissions.

It is expected of all these homes to be super insulated and have solar PV panels on their roof. I was interested in innovative new approaches at achieving maximum effect (energy efficiency or energy generation) using the least expensive methods. In this regard, the Boston Solar home has (had) great potential, if not for the massive glass array on the northern side of the house. All these windows and doors will let all the heat escape in the winter, which makes it that much less efficient. This is a fixable situation however – just remove most windows and put a wall there

Despite potential heat loss, the liquid-filled glass units on the southern side of the house will collect tremendous amounts of solar heat and store it, making it much easier to heat this house. Find out more about these liquid-filled solar thermal windows and wall panels.

In addition to solar thermal wall panels, Boston solar home has about 6.4 KW solar pv system on the roof and a solar thermal hot water heater, for heating and domestic use. There are many other new and innovative design features used by BAC (Boston Architecture College) and Tufts University students in the construction of this home – too many to list here. You may check out the project’s website – www.livecurio.us.

Team Spain solar home:

Another solar homes that attracted my attention was the one build by Team Spain (which for some reason was doing VERY poorly in this competition).

Apparently, these bi-pv cells are very good at capturing indirect sunlight and help the house generate the most electricity it possibly can.

Team Spain used a very interesting )in my opinion) approach at capturing ALL available solar energy with their powerful solar PV array. This roof mounted array can rotate at the center, following the sun going across the sky, thus always keeping the most efficient angle of the PV panel to the sun. It is basically a gigantic solar tracking system, which is however complicated and expensive systems to implement, which make this house not as competitive in terms of costs and ease of building.

Additionally, the glass walls of this home have integrated solar PV cells, which captures even more solar energy. It is a good idea, but and overkill in my opinion, and the roof mounted solar system should be more than sufficient and, unless they used “dummy” cells on east, west and north sides of the house, it is a waste of solar capacity, as the sun will barely or never hit those solar cells.

Cornell University Solar Home:

Another interesting design, which for some reason reminded me of the Water World movie was a solar home built by Cornell University students. It featured three round “rooms” connected to each other, and a large solar PV system, which for some reason was mounted flat to the ground.

It may not be the best designed house (in terms of competition rankings), and round rooms make it ever more difficult to build, but the steel frame and a VERY cool vintage design made it very attractive. As I was writing this, Cornell’s solar home was in 6th overall place, with a few more contests to go. You can view current team rankings here: http://www.solardecathlon.org/scoring/

As a side note, as of Oct. 13th, Team Boston solar home is in 12th position and Team Spain is in 18th place, while 1st place belongs to Team California.

Let the best solar house win!

The Solar Decathlon will continue for another week or so, and there are a lot of contests left in which either team can pull forward dramatically. Therefore, I will not even try to predict the winner. All houses presented in the Solar Village this year were very well designed and built, and the green building technologies used in them will in the (hopefully) near future migrate into traditional construction markets and help home and building owners reduce the over all energy use and make our environment better. This competition is also an inspiration for the new wave of architects who will be literally building our future homes and infrastructure, and as you can see, they all have great ideas. I will continue the cover the Solar Decathlon 2009 in future posts, and soon you will be able to review the IB flat roof installation which we did on the Curio Home – look forward to seeing it soon on our cool roofing blog.

In 2007 Solar Decathlon, Boston was represented by a Solar Home built by the 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 the 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 the 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 needed. 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 roofs with cool roofs such as IB. Also, when roof removal is required by code, calling a skip hire to remove the old material, and then installing these new highly efficient roofs is an 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 has been 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 new and improved solar thermal windows: these are not the old 2×2′ window blocks. It will be a full size 8×2 wall/window units, covering the 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 grid, and won’t need any outside energy sources for either heating or cooling.

Portable design of this Solar Home:

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

The house is designed to be easily taken apart and put back together: All the mechanical components, bathroom, kitchen, heating and air-conditioning equipment and electrical panels 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 the 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 the 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  a 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 the competition site in Washington DC, and nominal expenses such as marketing, promotion, creation of the website, etc. So the actual construction costs are somewhere around $500,000-600,000.

This is just the 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 in 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 a perfect fit for any sloped roof design.

]]> http://www.greensolarcafe.com/green-construction/boston-solar-decathlon-home-with-ib-flat-roof/feed/ 1 http://www.greensolarcafe.com/renewable-energy/solar-pv-cool-roofing/ http://www.greensolarcafe.com/renewable-energy/solar-pv-cool-roofing/#comments Tue, 25 Nov 2008 20:33:42 +0000 Leo http://www.greensolarcafe.com/?p=26

Reducing Energy consumption to Maximize Solar PV system efficiency

Part II of solar PV design Guide:

As a rule  of thumb, an average house in the US will need about 5 kW solar system, to become self-sufficient, and  independent of grid electricity. As another rule of thumb, an average Solar PV system installed in the US is about 2.5 – 3 kW, and you still have to buy about half of your electricity from a local utility company.

Before you start shopping for a Solar PV system, you will need to do some homework, and it is also in your best interest to do the preparations, which will reduce your energy use. As a result, you will need a smaller Photovoltaic System.

On average, every dollar you spend on reducing resources consumption will provide 2 dollars in savings. Things you can and should do to reduce your energy consumption (even if you do not plan to have a solar system installed):

1. Get small florescent light bulbs – you should have done it a long time ago, as these have been available for years. Benefits include reduction in electricity use by 3 times. Service life of SFB is… well, I have a bunch of them that are 3 years old, and I have not had to replace a single one of them yet. I bought mine for $0.50 each, 4 years ago, from Ann & Hope in Cumberland, RI, and some from Building #19. You should have some similar discount retailers near you.
2. Replace your inefficient appliances with new Energy Star certified ones Do your research on energy savings. I calculated that if I replace my old fridge with a $200 new Energy Star fridge, I will recoup it’s cost in 1 year, as it contributes probably half of my $40 monthly electric bill. You can go to a Sears Appliances Outlet and buy brand new stuff for almost 50%  off in store prices.
3. Insulate your home! Over 80 percent of homes built before 1960′s, do not have any insulation. If you increase your insulation from a 3-r for a standard stick-construction walls with no insulation, to lets say 13-r by having a blown-in insulation installed, you will reduce your heating and cooling bill by 25 to 30 percent. Do the same to your windows. If you still have old, drafty single-pane windows, replace them with at least an Energy Star certified double-pane with Low-E film. the best option is to have a Triple Glazed, 2x Low-E, 2x Argon or Krypton gas premium window, that can go to almost 10-r value. Insulate your doors with weather-stripping. A lot of cold air enters the house through the doors, especially, if there is no second door. If you make your home super-insulated, your heating/cooling bill can be reduced to almost 10% of its original amount. That is a 10 times reduction, for which you pay only once, and it will save you money for years to come!
4. Install Low-Flow shower heads and 1 gallon per flush toilet. Whether you are a landlord or a homeowner, your water bill has probably sky-rocketed in the last couple of years. Mine definitely has gone up 30% in last 3 years.

Have a Cool Roof installed

While most heat loss in the winter occurs through the windows, in the summer, most of the heat gain occurs through your roof. Most homes in the US have an asphalt shingles roof, which is not only bad for the environment, but also contributes 90% of the solar heat gain. Even light-colored asphalt shingle attract solar radiation, transfer it into the attic and also act as thermal mass, by storing most of the heat gained during the day, and keeping you attic steaming hot at night, making the AC work around the clock.

Whether you do or do not plan to have a Solar PV system installed (be it on the roof of your house or ground-mounted array), your firs concern must be to reduce your energy use. This is especially true if you actually plan to have a solar electric system installed. A cool roof can reduce you Cooling cost by 25% or more and can help you trim your solar PV system requirements by as much as 1 kW. At $10 to 12 per watt of solar PV system, you are looking to save $10,000 to 12,000 before any incentives or tax credits.

Choices of Cool Roofing for Residential and Commercial use

A good example of a cool roof would be a Metal Roof coated with Kynar 500 Cool-Roof certified reflective coating. You have a variety of architectural styles and choices of metal available to you. From Standing Seam metal roofing to Aluminum shingles, to Steel Slate or Tile impression to Heavy Cedar shake, Spanish Tile, etc. As for material, your two basic choices are Steel and Aluminum, with Zinc and Copper being on the exotic side, as well as the more expensive options. If you look to integrate Uni-Solar Thin Film laminates to Standing Seam metal roofing, you want to go with a steel panel, as aluminum’s expansion/contraction ratio is more than that of Uni-Solar’s PV modules.

If you own a home or building with a a low pitch or a flat roof, the most economical and greenest choice for you is to use a IB CPA/PVC single-ply roofing membrane, which has a Cool roof acrylic coating, featuring over 90% solar reflectance. IB roof is also a long lasting roofing membrane that features hot-air welded seams. The welded seams create a permanent bond between two sheets on membrane, effectively eliminating the possibility of a roof leak.

Planning a Solar PV system

Solar electricity is probably the most expensive form of electricity, yet it is very popular due to some constrains associated with other forms of renewable energy. Wind power for example requires an adequate amount of land and the turbine must be located above the trees and surrounding structures. This limits the use of wind turbines mostly to rural areas. Small hydro-electric systems require a water stream or a river near your house or building, which also limits it’s use to certain locations. Solar on the other hand can be installed almost everywhere, as long as there is unshaded southern exposure and an adequate installation area. Solar PV can be installed on the ground, on the roof of a house, barn/garage, sky-scraper or a warehouse. It can be installed in an urban environment – grid-tied, as well as on a remote unpopulated island – off-grid.

With Solar you also have a variety of architectural styles, panel types and mounting methods available. The most popular (yet, least efficient) is to mount mono or poly-silicon solar panels right to the asphalt shingles roof, using mounting rails and brackets.

]]> http://www.greensolarcafe.com/renewable-energy/solar-pv-cool-roofing/feed/ 0