Posts Tagged ‘passive design’
The Eco Builders Guild, South Sound chapter is proud to announce the second annual South Sound Green Tour coming April 16th & 17th. We started the Green Tour last year and it was huge success. Just like last year, we will feature houses and commercial sites that represent the best in green building and sustainable practices. The homes are located through out Thurston County, including Tumwater, Olympia, and Lacey. We will also have workshops at each site demonstrating many of the features of each site. This year we have also added an expo which will be located in the new Lott buildings parking lot. It will house lots of vendors offering a huge array of green products and services.
Another big addition to the tour is that the Seattle chapter has joined in with us and will have a tour of their own on the same weekend. For more information, or if you would like to be a vendor or site sponsor please visit http://www.ecobuilding.org/events/2011-green-home-tour.
1. Shades, Awnings, Blinds, Curtains and even foliage around the windows can affect solar heat gain and can also be a cheap way to cool the house.
2. There are five parts of a window that affect its energy efficiency: Glazing technology; Frame; Operating Type i.e. how it opens and closes; Low-E coatings; Gas fills; Spacers. You need to check all these aspects of a window and ensure that they are the best suited for your climate.
3. Depending on the kind of problem you think you’re likely to have, focus on each of the six parts mentioned above. For instance:
a. If you live in predominantly warm and sunny climate, then you will need to focus on Glazing, Low-E coatings
b. If your weather is humid, then attention to spacers, frames and operating type will keep condensation and leakage problems in check
c. In cold climates, glazing, frame, spacers and gas fills need to be checked well before buying
4. Energy-efficient mortgages are a way of paying for energy efficient windows, which typically cost more than regular windows. This actually turns out to be quite cost effective, because the savings on energy and utility bills arising out of energy-efficient homes offsets the monthly mortgage payments. To get more details, visit the energy department in your state.
5. Important: Get your energy efficient windows installed by a professional. If not installed properly, they will be less efficient than even regular windows. . Make sure your installation expert has experience in installing windows and is familiar that particular manufacturer.
Sometimes getting the U-Factor, SHGC and VT values right is not enough. Often, the installation of the window itself, i.e. the entire window assembly can have flaws. These flaws result in air leakage – one of the main obstacles in trying to achieve energy efficiency with the help of windows.
If your house is built on the Passivhaus principles; or you are looking at seriously reducing your HVAC requirements (and thus the bill) then air leakages through windows can punch a large through your plan. Some energy efficient windows specify the AL value (expressed in cubic feet of air passing through for every square foot of the window assembly) between 0-1. The lower the value, the lesser the leakage. The industry-accepted value is 0.30.
Another problem for insulation is condensation. If you live in cold areas, you’ve probably seem frost or dew on the edges of the windows. Looks quite ‘Christmassy’ but it only means that much more heating load. Condensation happens when inside warm air comes into contact with cold panes and glass, which essentially means your windows are not doing such a good job insulating.
With condensation and air leakage, there aren’t fixed ratings to go by. However, certain materials and window technologies work better. For example, if you’re opting for multiple pane windows, looks for stainless steel spacers, or thermally improved spacers made from silicon foam or butyl tape. These spacers might be more expensive, but they are better are insulating, sealing and thus preventing unwanted heat transfer, while at the same time allowing from seasonal expansions and contractions in panes. Similarly, opting for energy efficient windows with two or more panes or glazing reduces condensation even at indoor humidity levels of 45-60%. This is especially true of windows with argon/krypton glass filled windows.
It is very evident that the larger your window, the more natural light it will bring in. Depending on the positioning of your windows, and its visible transmittance (VT) value, your windows could provide you with enough natural light to greatly minimize if not eliminate electric lighting requirements during daytime.
VT values are generally given between 0-1. A rating of over 0.70 is the highest you can get with clear glass windows devoid of any coatings or tints. The more the number of panes, coatings and tints the lower the VT value.
A high Visible Transmittance has another advantage – it eliminates the cooling function which is usually required in a house that uses electric lighting. A high VT value is especially important when a home is built using passive house principles or design.
However, one thing to consider when it comes to VT, is that a window with a high VT value, will also admit that much more solar energy (heat) inside the room. Thus, a clear glass window with a VT of 0.8 will also have an SHGC of over 0.60 – something not at all desirable in a warm or sunny climate.
To get around this, one can use Low E coatings, which are invisible, and yet block heat gain considerably. These coatings also protect indoor furniture and upholstery from the damaging effects of UV rays. Another way is to have operable windows that you can open up to air the room out frequently. Needless to say, a good ventilation system is important when you have large windows and a sunny climate.
For windows that are low on SHGC and high on VT, look for a high Light-to-Solar gain ratio. This determines how much more light is let in without adding to the heat.
South Sound Chapter
The South Sound Green Tour
Innovation – Education – Inspiration
April 17th and 18th, 2010
A community event to celebrate green innovations through education in sustainable building and inspired living.
This year’s tour will showcase the greenest homes and buildings in our area that incorporate significant use of solar or other renewable energies, new and reclaimed materials, low energy consumption and water conservation technologies, and sustainable design techniques.
Educational sessions will be held at various locations and feature real life topics on how to build and live greener. See our website for more details – www.SouthSoundGreenTour.com The site will be running by January 1, 2010
The Cooper project that we have been building will be one of many homes and businesses that will be open to the public for the weekend. Mark your calenders and join us, it should be a great time
The Northwest Eco Building Guild is an alliance of builders, designers, suppliers, homeowners, and partners concerned with ecological building in the Pacific Northwest.
A vital organization, our mission is to provide leadership in education to transform the built environment and build a sustainable society.