hvac design
It is unusual to employ computer modeling techniques in the design of a residential building. However, to achieve the greatest efficiency, the HVAC team built computer models to track and monitor energy usage. For example, heating and cooling systems were sized using a series of calculations to estimate the heating and cooling necessary on the hottest and coldest days (see chapter 29 of the ASHRAE Handbook for more information). In order to create a more energy efficient home, we selected the minimum size system that would meet our anticipated heating and cooling requirements.
The energy needs of our house were modeled by a free program called eQuest. The program asks a series of targeted questions about the construction and components of the house and then estimates how much energy it will consume by month. It further breaks down how this energy is used (lighting, hot water, heating, cooling, ventilation, etc.).
To further maximize the efficiency of the house, our ventilation strategy was simulated using Integrated Environmental Solution’s Virtual Environment. IES Virtual Environment incorporates computational fluid dynamics (CFD) to simulate how air flows throughout the house, so that temperature differences between rooms can be diminished. As a result of these tests, vents were placed near windows to stabilize the temperature differences of windows.
In determining the optimal HVAC design, we considered other alternatives. We did not use radiant flooring as a method of heating because of its constant need for hot water. For a typical house, electricity is always available, and can always be produced by the boiler. In our house, however, hot water is produced by transforming the sun’s energy into thermal energy, and hot water is stored in tanks. Because the house would require hot water overnight for radiant flooring, a large hot water tank would be required for storage. In the end, we did not feel that this system would be well suited for a self-sufficient house.
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Products:
- IES Virtual Environment software – Total Retail Cost $8,400 (donated)
- eQuest software – Available for free download at: http://www.doe2.com/
