Tomorrow's Environment: Commissioning Your Building Envelope
What is commissioning a building envelope? Well, it is just another term for implementing step one of any energy audit by taking an infrared survey of the building. When done, it includes an infrared of the exterior walls, windows, overhang, foundation, and roof. It also includes infrared of the windows from the inside too.
Commitments and Leaky BoatsI heard there are more than 1,000 college and university presidents who have made commitments to their students, alumni, and faculty to reduce their campus carbon footprint (e.g., 30% by 2014 benchmarked to 2006 energy consumption). Unfortunately, I haven’t seen or heard of any college or university truly demonstrating this commitment, because none of the institutions I’m familiar with have invested in an infrared survey of their buildings.
An infrared survey is a relatively inexpensive process to perform, and I’m not sure why it isn’t done. Instead, the focus is on the mechanical and electrical systems within their buildings. Energy retrofitting mechanical and electrical systems can be complex and costly to assess, and even more costly to implement, operate, and maintain the high-performance control systems that frequently result from these studies.
One way to look at this is to compare it to replacing an old boat motor with a new, energy-efficient hybrid motor. At first glance, you would think you did the right thing. But what if the boat had other problems, such as leaks? You must do one of three things: seal the leaks; purchase an energy consuming bilge pump to continuously remove the water as it leaks, which will consume pump motor energy that will offset some of the energy you saved from your hybrid motor; or do nothing and let your boat with its hybrid motor sink to the bottom of the lake.
Three OptionsYou have three options with regard to the building energy audit. First, complete an infrared survey and see how tight the building is and, in the case of the roof, find out if the roof insulation has lost some of its insulating value because of past roof leaks.
Option two is go right to that hybrid boat motor concept and add sophisticated controls. This will reduce energy consumption while adding a few additional perimeter heating devices to offset the cold spots that are now occurring because the new automatic control system and rebalanced the HVAC air and water systems can’t keep up with the excessive infiltration.
The third option is to reduce energy through the high-performance control systems and rebalanced HVAC systems, and live with the newly created infiltration cold spots in the building. I guess you could explain away the cold spots by saying the space thermostats have been reset to a lower temperature to save energy in the quest to reduce the carbon footprint. This may sound like a good answer, but those occupants in rooms that are 60°F may not be convinced.
The fact of the matter is that to conserve energy without compromising reasonable space comfort, you have to start with a tight and energy-efficient building. Once you know the building is thermally efficient, you can proceed to the next step in the energy auditing process, which is to look at HVAC, plumbing, electrical power, lighting, and building equipment and systems.
The same applies to new construction and building renovations. Recently, we commissioned a $40 million renovation that had all the high-performance features you would expect for a job that was in compliance with LEED®, but it was not certified as LEED. The only work that was to be done on the perimeter was to replace the old, inefficient single-pane glass windows with energy efficient windows. Midway through the construction, the owner agreed to have us implement a building infrared scan as part of our commissioning process. Thinking ahead, I was expecting to find the existing roof would probably have some hot spots where the existing insulation had failed over time because of water damage. Instead, what we found was that 52% of the infrared deficiencies were the new windows!
Who would have figured the weak link in the energy conservation process would be those high-performance windows? Had the owner chosen not to commission the building envelope, everyone would have been pleased with the project and the facility staff would have been left with a building that was consuming more energy than the design team had projected in their energy software simulation.
When it comes to implementing an energy audit or to commissioning a capital project, step one is commission the building envelope. If you don’t infrared the exterior, your energy investment dollars will leak out of your building, sinking your building program. ES
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