Equinox House is a modestly windowed home. At the same time, the windows have been designed to brightly light the interior throughout the year, and efficiently provide solar heating in the winter. The house is named after its novel “equinox overhang” that protects the clerestory windows from the summer sun while acting as a solar radiation reflector during the winter.
Windows are generally misunderstood and poorly incorporated into building design. Very few people are able to provide quantitative information on the cost and value of a window. Sales personnel are unable to supply answers, and are most interested in selling you as many windows as possible.
In almost all cases, windows do not save money. They are the most expensive part of the house exterior and require the most maintenance. The most “economical” house would be a Styrofoam igloo. So why do we want windows? We like to “see” outside, and we like natural light. With the cost of flat screen televisions dropping to that of a window ($40 to $80 per square foot), perhaps we will replace windows with a series of televisions and exterior cameras that transmit the outside view in a more energy and cost efficient manner than a window? And, with the added benefit of being able to change the view to that of any location in the world if the outside view isn’t to your liking.
The windows in Equinox House provide wonderful, unobtrusive lighting throughout the year. During the summer when the equinox overhang eliminates unwanted “beam” solar radiation, a uniform 400 lux light level, comfortable for reading, occurs throughout the living areas. During the winter, light levels increase above 400 lux as beam solar radiation is allowed in on sunny days to provide beneficial heating as well as daylighting of the interior. Clerestory windows distribute the sunlight in a manner that keeps upholstery fabric protected from harsh sunlight levels as well as protects occupants from glare and overheating. North facing windows have been used to provide occupants with a pleasant view of the gardens in a manner that gives a sense of openness without significant loss of building energy performance.
Choosing windows is a daunting task. What levels of SHGC, U-factor, and VT are acceptable? And what are the SHGC, U-factor and VT, anyway? To learn more about the design, performance and cost of windows, read our ASHRAE Journal article from December, 2010. And then, choose your windows very carefully.
