NREL Building seeks Net-Zero Status

LINK - Pushing the limits of net-zero energy building design.

 


This building in Golden is worth visiting...

Shouldn't every new building be Net-Zero?




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Frost on Windows

This time of year in Colorado, when nighttime temperatures get down to 20 below zero, we get calls from people worried about frost on their windows.  The beautiful crystalline pattern of the frost is not appreciated when it thaws and drips onto the window sill, creating a problem for the homeowner.  This moisture can soak into a wood sill, degrading it and causing discoloration.  Eventually, if it keeps happening, there is the potential for mold growth.

Why does this frost occur?

Its all about dew point, the temperature for a given relative humidity at which airborne water vapor condenses on surfaces.  So, when the surface temperature of the interior pane of the window is below the dew point, condensation on the glass surface will occur.  The dew point depends on both temperature and relative humidity.

What can you do to avoid the frost?

1 - Use high-performance glass.
In snow country, we recommend using a high-performance glazing product like a triple-pane window.  The better the insulation value of the window, the higher the temperature of the interior glazing surface, and the less likely it will be to frost. 

2 - Use insulating shades appropriately.
Many of us are using insulating shades to increase the R-value of the window assembly, a good idea, but consider this:  Even though your insulating shades help keep the heat in the room, they also help keep the cold on the glass.  Unfortunately, since there is not a true air seal between the insulating shade and the glass, the shade allows moisture-laden air into that space.  There it will condense onto the glass surface, causing frost on those cold winter nights.  In order to keep from having frost on the window and subsequently water droplets on the sill, Mike Dollahan of Architectural Windows and Doors recommends keeping the insulating shades open at least 4" at the bottom.  This allows warm air from the interior to heat the glass surface so that it does not drop below the dew point.

3 - Watch your home's interior relative humidity.
In Colorado, an interior relative humidity of 25% to 35% is normal.  But if you are humidifying your home, or if you have a pool or hot tub inside, relative humidity levels will go up.  As they go up, the chance for frost on the windows goes up, too.  (you may want to buy a hygrometer to keep tabs on those humidity levels!)

4 - Use fiberglass or vinyl windows.  The frames of these windows are typically better insulated than wood-framed windows, and they won't discolor or become saturated when the frost thaws and drips on them.   Fiberglass windows are considered to be the best choice for overall performance and longevity.  The process of making fiberglass is not too impactful; and its made from a very abundant resource, ...sand!

Net-Zero Energy Monster homes?

Here is a great little article in Living Green Magazine by one of our local green gurus, Auden Schendler: http://www.livinggreenmag.com/archives/green_building/net_zero_homes.html

Architecture in the Roaring Fork Valley

Here is a radio interview I did on KDNK about the state of the economy and its effects on the local architectural community.

la Fête des Lumières de Lyon

You don't have to speak French to enjoy these amazing photos of the Light Festival in Lyon, where I used to live!

HIS or HERS?! The EnergySmart Home Scale

The HERS Index...   you may be hearing a lot about it, but what is it?  (currently this rating is being re-branded as the "EnergySmart Home Scale")

















The HERS Index is a scoring system in which a home built to the specifications of the HERS Reference Home scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home's HERS Index, the more energy efficient it is.

Each 1-point decrease in the HERS Index corresponds to a 1% reduction in energy consumption compared to the HERS Reference Home.  So, a home with a HERS Index of 85 is 15% more energy efficient than the HERS Reference Home and a home with a HERS Index of 65 is 35% more energy efficient.


If you're buying a new home ask to see the HERS Index!  (if the home doesn't have one, get it tested!)

If you're building a new home, make sure to ask your architect to design it for a specific HERS Index.  (70 or lower is a good goal and also the threshold to meet the DOE's Builders' Challenge)

Stay tuned for info on Green Line Architects' Net-Zero Energy Home being built high up in the Colorado mountains.

House Size Matters?

This Japanese home is extremely space-efficient, and besides the lack of art on the walls, looks very livable.

Could you be comfortable living in roughly 825 square feet?

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