In this 3-part blog series, Cherie breaks sustainable design into three steps. The first covers reducing energy use through Passive Heating and Cooling, the second covers options with Mechanical Systems, and the third covers Indoor Air Quality, Water Efficiency and Sustainable Materials.
Passive Heating and cooling:
Arguably the most important aspect in creating a green home is designing a home that uses as few natural resources as possible. A key component is reducing energy use through passive heating and cooling. We use 3d modeling to take the guesswork out of passive design solutions. 3d modeling calculates a home’s energy loss, energy use and heat gain. This provides us with direct feedback to determine the best placement of windows and type of glazing, the amount and type of insulation used, the size of overhangs, and the selection of a heating and cooling systems. In general, passive heating and cooling techniques are economical, and get the most bang for your buck in achieving a low energy use home. Here are some basics in passive heating and cooling techniques to consider:
Insulation and Air Infiltration:
As a rule of thumb, relatively inexpensive items such as insulation and sealing go the furthest in reducing the amount of energy loss or gain. Insulation technology has come a long way and sealing up potential air leaks through joints in the construction is critical. Foam insulation provides a much better thermal performance than batt insulation and reduces air infiltration. Smart designs also seal up energy gaps that are often overlooked, such as rim joist insulation, insulation at the foundation wall, and under basement slabs.
Good windows and glazing options have significantly advanced in the last 20 years. In fact, there are many options allowing us to select different glazing based upon the window’s size and location in the home. For example, on the east and west you want to limit the amount of solar heat gain – while on the south, you may want to allow some solar heat gain for passive heating in the winter. Basic passive design knowledge, combined with 3d modeling helps us determine which is the right glazing for a given location.
Roof overhangs, awnings and other shading devises:
These are particularly successful on the south windows where you want to reduce the heat gain in the summer, but allow for heat gain in the winter. Our 3d models combined with the energy modeling can determine the precise size of overhang required to optimize summer shade and winter heat gain.
It is best to orientate the house so the largest mass and windows are located on the south and north. This is not always practical on the Front Range where it is desired to locate the house to capture views of the mountains to the west. Eliminating hot summer sun on the west can be tricky. The best way is to locate and exterior shade such as retractable screen and landscaping that can block low, horizontal sun without blocking the view. High tech glazing can significantly reduce heat gain on west facing windows.
Passive heat gain:
Surprisingly enough, we find that in our climate it is as critical to control the unwanted heat gain as it is to provide heat in the winter. A careful balance between desired heat gain in the winter with unwanted heat in the summer needs to be met. Well-placed internal thermal masses – such as concrete floors or stonewalls, combined with the right type of glazing and external shading can work well.
The stack effect:
Natural ventilation and air movement can be achieved by the stack affect. In the cooling season, hot air rises to a high point in the structure to open windows or other ventilation. The warm air rising reduces pressure in the lower portion of the building thereby drawing cool air in at the lower levels. Active ventilation as simple as well placed operable windows can cool down the house at night and keep it cool in the day.
Other means to reduce energy use:
- High efficiency and energy star appliances
- Reduced lighting, lighting on dimmers or controls
- Window shades
We promote an integrated approach to sustainable design; employing interdisciplinary team of engineers and designers to explore and evaluate potential green design opportunities from the earliest planning stages.