An Energy Efficient Building Shell From Recycled Materials
The outer shell of the Exit 20 Green Office Building will be constructed of Durisol blocks, an insulated concrete form system which combines cement-bonded wood fiber material and mineral fiber insulation. The wood fiber comes from recycled waste wood; the insulation, cement, and concrete core are made partially from steel production waste. These blocks contain thermal, acoustical, and fire protection properties and they achieve insulating properties (R-28) not possible with other concrete form systems.
Taggart Construction has been working with Durisol Building Systems, Inc. to develop an advanced version of their building block. These blocks will set a new R-value standard for this type of construction, and they will be used in the construction of the Exit 20 Green Office Building.
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Efficient, High Performance Windows
Ultra-high thermal performance windows from EFCO and Accurate-Dorwin will complement the energy-efficient building shell. The atrium windows, in contrast to most inefficient curtain-wall systems, are comprised of "quad-panel" glazing: two outer glass panes sandwich two films of heat mirror film. This design provides a center-of-glass R-value close to that of an insulated wall. Sophisticated energy modeling on the new building indicated that heating and cooling the Exit 20 Building will require about 50% less energy than a traditional office building of similar size.
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Efficient, Earth-Friendly Heating and Cooling Systems
The Exit 20 Building features a Ground Source Heat Pump for heating and cooling. The combination of the well-insulated building with the Ground Source Heat Pump will minimize the amount of energy required to control the internal temperature of the building. This zero-emissions geothermal system will rely on two 1,500-foot wells to transfer heat energy to and from the earth. Tailings from drilling the two geothermal wells will be re-used on site as part of the base for walking paths and parking lots. Pre-construction energy modeling was used extensively to determine "right-sized" mechanical systems to achieve optimal efficiency.
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Energy Recovery Ventilation
As fresh air is brought into the building's ventilation system, advanced Energy Recovery Units will heat or cool this air by capturing and transferring the temperature differential of the outgoing exhaust air. Thus, for example, when it's 20 degrees outside, the incoming ventilation air can be warmed to 50 degrees or higher by a heat-exchange in the ventilation system. This takes place when the incoming air passes by the outgoing air. The geothermal heating system can then heat this incoming air another 15 degrees to bring it up to a normal indoor temperature of about 65. The result is an enormous energy savings because the geothermal system only has to heat the incoming air from 50 degrees to 65 degrees instead of from 20 degrees to 65 degrees.
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Solar Shading Devices
Strategically placed photovoltaic (PV) panels will act as fixed south-side window shading to reduce heat gain during the summer months. These dual-purpose PV sun shades will reduce the energy loads for cooling the building and will generate "green electricity" that can be used by the building's occupants and in the building's electrical and mechanical systems. Excess electricity generated on site will be put back into the power grid for use by others.
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On-Site Electricity Generation, Renewable Energy Credits
Additional photovoltaic arrays are planned for a VIP parking area close to building's entrance on the Southern exposure. These PV sun shades are much larger than traditional window shades, and they can provide cover for several tenant and visitor vehicles. One idea is to allow the winners of a building-wide energy reduction competition to park in this area.
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