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 enters 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 to the liquid prevent stain deposits on the inner walls if the unit. In the picture above, these units are used as building blocks, and cover almost 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, the sun is much higher and with appropriate shading, these thermal mass windows keep the home well insulated without collecting any heat. Additionally, a special low emittance 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 will not 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 of the windows. I’ll build special shelves to make the process of putting them up for the winter, and removing them in the summer, easier.

Traditional Sash Windows – Thermal Performance Solution

Here is how to make your traditional sash windows more energy efficient…

Sash Windows

Traditional vertical sliding sash windows, are based on a simple design of two of sliding glass panels (top and bottom sashes) and have been part of the UK’s architectural heritage for over three hundred years. The sash window originates from 17th century England, where the first prototype, the single hung sash window, was created by Robert Hooke, an inventor specialized, among others, in mechanics and architecture. The first type was more basic than those created nowadays and can still be seen in some historic buildings, predominantly of aristocratic ownership.

Solutions

Instead of replacing traditional sash windows, there are multiple reasons why owners should opt for restoring them to their initial appearance and at the same time optimize their thermal performance.

Traditional Sash Window

Sash Window Repair

The restoration process is ideally to be carried out by specialized companies and is always adapted to the specific type of sash windows and its particular deficiencies. Common sash window repair works include, replacing sections of the box frame normally the lower section of pulley stiles, lower sections of outer linings, bottom rails and window sills and replacing missing puttying and repainting. Using traditional carpentry and joinery methods with advanced modern epoxy resins ensures a permanent repair. This process does not alter their original appearance but instead, mends the alterations brought to it by time and natural phenomena.

Sash Window Draught proofing

This is also very effective process if done correctly it maximizes heat retention in the home and minimizes heat and energy loss. Sash window draught proofing is less known perhaps, yet once a sash window has been overhauled and draught correctly, even old sash windows can equal modern ones in terms of energy efficiency.

In this process the staff beads and parting beads are replaced with new beadings with a draught proofing material permanently machined into the beads, top and bottom sash re-fitted and also fitted with a draught proofing material (usually a brush pile). The 4no sash cords are replaced and the counter balance weights are re-

Sash Window Draught proofing

weight to the correct counter balance ensuring the sash close with a minimum gap.

Resources:

Find more green Home Improvement Ideas at Green Home Ideas blog.

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.

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