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By Greg Zimmerman, Executive Editor
June 2008 -
Building Automation Article Use Policy
A building with low-e glass should see lower heating and cooling bills. But low-e glass raises the first cost of the building. And for many buildings, the promise of lower energy costs isn’t enough to justify increasing the construction budget.
End of story? Not necessarily. Suppose the mechanical engineer and architect sat down with the facility executive during the design phase and agreed to install low-e glass, then downsized the HVAC system to account for the lower heating and cooling loads provided by the better windows. Savings from the smaller HVAC system would be used to pay for more efficient windows — and maybe for more insulation.
Opportunities for efficiency in building systems interactions emerge only when facility executives look at their buildings holistically, not system by system. This means using an integrated design process in which facility executive, architect, engineer and even contractor all sit down at the same table to talk about design.
In the old, linear design process, the members of the project team would barely talk to each other. “The disadvantage when all the construction divisions were made was that it became harder to cross lines between mechanical, electrical and structural,” says Gary Christensen, developer of the LEED Platinum certified Banner Bank Building in Boise, Idaho. “Decisions were isolated.”
Fortunately, designers are moving away from that idea. Many opportunities for creating efficiency with complementary strategies involve ways to downsize and then optimize HVAC equipment, such as using a cool roof to lower cooling demands in the hot summer months, or using a raised floor with an underfloor air distribution system so that a smaller volume of air on each floor needs to be heated or cooled. Raised floors also have the benefit of creating flexibility should the requirements for a space change. Both Christensen and Joe Kuspan, lead designer of the Dell Children’s Medical Center in Austin, Texas, used raised floors in their administrative and office space for energy efficiency and flexibility reasons.
“We used a raised floor so we’re not heating and cooling air above people’s heads,” says Kuspan.
LEED has been a boon to the notion of creating efficiency with complementary building systems because it helps foster integrated design and encourages facility executives and design teams to get creative about efficiency strategies. Additionally, the increasing sophistication, availability and affordability of energy management software, building information modeling and energy modeling software has helped facility executives create scenarios to understand better how systems work together.
Retrofits can miss energy gains if upgrades are simply replacements of existing equipment. New lamps and ballasts in existing fixtures may save energy, but if the space was overlit, it will still be overlit after a one-to-one replacement of lamps and ballasts.
An upgrade is the right time to look at options. If old HID lights in a gym are due for replacement, high-bay fluorescent fixtures may be a better choice than metal halide. Replacement of a black, heat-absorbing roof is a chance to consider a reflective roof, as well as extra insulation.
Facility executives who want to turn a replacement into an upgrade shouldn’t wait until the last minute. For example, if a 500-ton chiller fails, there may not be time to decide whether a pair of 250-ton units would be a better choice, let alone whether 500 tons is the right amount of capacity.
— Edward Sullivan
For steps to lay the groundwork for an HVAC upgrade, go to: www.facilitiesnet.com/5919BOM
For dozens of links to design guides and examples of building elements working together for maximum efficiency, go to: ENERGY STAR's Design Guidance
For instructions on doing energy audits in existing buildings, go to: Flex Your Power
For a look at integrated design, go to: www.facilitiesnet.Com/2138bom