Early Steps in Making our Knoxville Office More Efficient

For over five years, the Southern Alliance for Clean Energy has maintained our Knoxville office on the 100 block  of Gay Street in downtown. We are proud to announce that we have recently purchased a new building at 3804 Middlebrook Pike, just west of downtown, that now serves as our Knoxville facility. This new space offers more room for our expanding staff, and will provide SACE a mechanism by which we can demonstrate energy efficient technologies and renewable energy generation at work.

We have already begun the process of retrofitting our new building so that it is more efficient, and are looking forward to becoming a model by lowering our carbon footprint and showcasing clean and efficient small business operations.

The new office building has a number of positive features and offers numerous opportunities for growth. It was, however, immediately clear that no serious effort has been made in the past to improve the building’s energy efficiency. One of our first steps after the purchase was to contract with a local home and business rating service to use blower doors to evaluate the air penetration of the building. Due to the complete lack of previous efforts to tighten the building, there were so many air leaks that the raters were actually unable to achieve an effective pressure reading.

The main problems were the lack of  insulation in the attic and the many penetrations through the drop ceilings for lights, speakers, alarm systems, etc. This prevented any effective “building envelope,” meaning that heating and cooling efforts were img_0397largely going right out of the top of the building. We determined that the best way to develop a better envelope was to use open-cell spray foam insulation. Open-cell insulation was preferable to closed-cell for two reasons: First, leaking water is visible through open-cell insulation, which is beneficial for roof installations because it mitigates the risk of invisible rot. Second, the blowing agent used for open-cell insulation is water-based, so the process does not emit the dangerous, powerful greenhouse gases involved in blowing closed-cell insulation.

We worked with Pioneer Heating & Air Co. and CFI Insulation to inject our external walls with InsulSmart Interior Foam and coat the underside of the entire building’s roof with five inches of Sealection 500 foam. Our new insulation provides an R-Value of 4 per inch, so our 5-inch thick coating gives us an R-Value of 20. We further benefited from the fact that our roof deck is now sealed more tightly. The combination of the tighter building envelope and our new insulation gives us an ‘effective R-Value‘ of 42. The insulation also brought the attic area  into conditioned space, which has an additional benefit because the the duct work for the HVAC system runs in the attic. Having the duct work in a conditioned space reduces HVAC losses between 25 and 40 percent .

The Middlebrook Pike building has some interior offices, including a conference room, with no img_0410windows or external lighting, as well as an internal hallway with no access to windows or external lighting. To address this issue, SACE decided to utilize solar daylighting fixtures. We worked with Home Building Supply to install Solatubes to implement daylighting for the hallway, conference room, and internal offices. We now have a total of seven solatubes (three 10″ tubes and four 14″ tubes) in our facility. Solatube offers a commercial solar daylighting application, but due to timing constraints and the need to move forward with the foam insulation quickly, we chose to use the smaller, residential versions. These work wonderfully; and thanks to these daylighting features, we have significantly reduced our need for electric lighting during daylight hours.

To further improve the lighting in our new building, we upgraded over 60 outdated florescent electric light fixtures, many of which had old magnetic ballasts and T-12 florescent light bulbs. These older models were very inefficient and noisy, and created img_0405a low quality office lighting. We once again worked with Pioneer Heating & Light to replace these lights with a higher quality, quieter, and more efficient T-8 lighting system, which is now in place in the majority of our lighted units. We anticipate that this step will lead to a significant decrease in our electric load. It has already vastly improved the lighting quality in our offices – and because we get a higher quality of light from each bulb, we are able to use a lower number of bulbs in each ballast to achieve optimal lighting. Note in the picture to the left: only two florescent tubes are necessary in each four-tube ballast.

Once the lighting and insulation retrofits are complete, we will conduct another blower door test to determine where additional air leaks exist in order to tighten up the building. We are also evaluating the current HVAC system, which consists of four separate units that all appear to have a relatively low S.E.E.R. (Seasonal Energy Efficiency Ratio) ratings of approximately 10. SACE is exploring opportunities to install a geothermal HVAC system, or, at minimum, a highly efficient heat pump or natural gas unit.

In addition to considering HVAC retrofits, longer-term plans will include taking advantage of the building’s south-facing orientation, and potentially utilizing solar panels.

Stay tuned for additional information and updates on how we continue to upgrade our new building to make SACE a model for energy efficiency.

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1 Comment

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Steve, Does Knoxville Utilities Board have any programs that SACE can take advantage of to accelerate its efforts? Any good advice? Or do we have to do this all on our own initiative? (Which isn’t so hard for us since we understand the options fairly well.)


Comment by John D. Wilson on January 28, 2011 11:14 am


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