Solar Zoning and Energy in Detached Residential Dwellings
J. Niemasz, J. Sargent, and C. Reinhart. SimAUD, 2011Review by Scott Schuetter, Energy Center of Wisconsin:
The amount of solar energy that a building receives in a year greatly affects its energy usage. In densely developed areas, a building can shade its neighbors, thereby impacting their energy usage. The Solar Envelope is a zoning tool that specifies limits to a building's size, such that its neighbors are guaranteed a certain amount of daylight. The Solar Envelope is specific to the building's latitude and normally is sized such that any building whose extents lie within it will not cast a shadow on its neighbors for a specified amount of time on the winter solstice (i.e. from 10:00 am to 2:00 pm).
This paper studies the impact of Solar Envelope zoning on a building's energy usage for 7 representative U.S. cities. An EnergyPlus model was developed of a typical two-story wood-framed residential detached. The model was then surrounded by buildings such that it was guaranteed a specified number of hours on the winter solstice. The number of hours was varied to show the impact of different solar zoning strategies.
A low number of hours would correspond to a densely developed neighborhood, while a larger number of hours would correspond to a sparsely developed neighborhood with plenty of solar access. The modeling showed that across all seven cities the energy cost actually increased when 6 hours of solar access was compared to effectively 0 hours. However, in the heating-dominated climates, the energy usage did decrease.
It should be noted that the shading was not optimized for each climate, but rather the same shading technique was applied to all climates. Finally, the authors point out that even though a building's energy usage may have decreased, using Solar Envelope zoning may still have a net increase in energy usage. This is due to more distance traveled by its occupants in cars and a possible decreased usage of public transportation.