When anyone moves into a new place, they start to think about the changes they want to make in their new home. The Southern Alliance for Clean Energy moved into our new home over a year and a half ago. Like anyone else we started to think about the changes we wanted to make. Of course, since we’re an energy advocacy group, most of those thoughts centered on energy use. When we first moved in, our building was an energy waster. Since then we’ve done a lot to make our new home more energy efficient.
Building Envelope Improvements
When SACE moved into our new building we had an energy audit done, and the auditors found some serious problems. There were several places where exhaust fans and ductwork penetrated the building envelope. There were a number of penetrations in the roof deck. In addition, the existing insulation in the walls and ceilings was old and, in some places, completely missing. Clearly, this building needed some sealing up.
So we had the folks from Pioneer Heating and Air Conditioning here in Knoxville, our heating and air conditioning contractors, take a look. Pioneer and CFI Insulation applied Sealection 500 spray foam insulation to the entire roof deck. This made up for the poor existing insulation and sealed up all the individual ceiling penetrations, bringing the effective R-value of the roof up to 42. They also applied InsulSmart Interior Foam in wall spaces where insulation was lacking.
Then they went around the building sealing up wall penetrations where various fans, ducts and vents had been. They also replaced old weather stripping on the doors and recaulked the windows. While the building is still not completely tight it’s a lot better than it was when we started. Having a better sealed and more insulated building allowed us to install a smaller HVAC system when the time came to replace the old units.
Lighting Retrofit
The building originally had a lighting system that was typical of commercial buildings at the time. Most of the fixtures were two-foot by four-foot four-lamp fluorescent fixtures with magnetic ballasts and T12 lamps. Each of these fixtures drew 144 watts.
As of July 2012 these fixtures and lamps will no longer be available on the market. According to DOE’s factsheet on fluorescent lamps (.pdf), “[lamps] that will likely be available on the market include high-efficacy T8 lamps and T5 lamps. Certain models of [lamps] (such as some T12s) are likely to become unavailable because, as currently designed, they are too inefficient to meet the prescribed efficacy level.”
We replaced the magnetic ballasts with electronic ballasts. We also reduced the number of lamps in most fixtures from four to two and replaced the old T12 fluorescent lamps with new more efficient T8 lamps. We cleaned the fixtures and installed new diffuser panels. All these actions reduced the wattage per fixture from 144 to 55. The light output per fixture was reduced 40% but the energy usage was reduced by 60%. The lighting retrofit cost about $3,400 and is saving us almost $1,300 a year.
Another innovative idea we implemented is the use of a high-performance daylighting system utilizing light tubes. You can see them in the main conference room and in some of the building’s hallways. These Solatube Daylighting Systems collect daylight at the rooftop and move it down through a reflective tube to distribute light evenly into a room through a diffuser at the ceiling. This provides free lighting into building areas that would otherwise be unable to get sunlight.
Geothermal Heat Pump
Next we replaced the old inefficient heating and cooling system. The old system consisted of four units. Each of these was a gas pack, combining a gas furnace with an electric air conditioner. Each gas furnace had an Annual Fuel Utilization Efficiency of 72%; each unit’s air conditioner had a Seasonal Energy Efficiency Ratio of around 11.
These older models couldn’t be installed today. In 2006 the U.S. Department of Energy set appliance efficiency standards for furnaces and air conditioners calling for an AFUE of greater than 78% and a SEER of greater than 13. DOE estimates that their appliance efficiency standards will save approximately 4.2 quads of energy by 2030 and will save consumers $1 billion, while reducing greenhouse gas emissions by 33 million metric tons of carbon.
These DOE standards are minimum requirements. We thought we could do better, so we brought in the folks from Pioneer to see what they could provide. They installed a new state-of-the-art geothermal heat pump system. This system was built around two Water-Furnace brand Envision Series split system units. The two units total seven tons of cooling. Each unit has an Energy Efficiency Ratio of more than 16 and a Coefficient of Performance of about 3.8.
While you can’t compare these efficiency numbers directly (SEER and AFUE are seasonal averages, EER and COP measure instantaneous performance) you can think of an EER of 16 as roughly the same as a SEER of 18. Also, an AFUE of 78% means that for every Btu of natural gas delivered to the unit, .78 Btus makes it into the heated space. A COP of 3.8 means that for every Btu of electrical energy delivered to the unit 3.8 Btus makes it into the heated space.
Why is a geothermal heat pump so much better? A heat pump doesn’t make heat; it moves it from one place to another. When the outside air temperature is low a traditional heat pump has to work hard to pump heat from the cold air outside to your warm living room. But the geothermal heat pump doesn’t do that. By running a series of pipes through the ground it takes advantage of the natural thermal characteristics of the earth. As you go deeper into the earth the daily and seasonal variation in temperature is gradually dampened. Once you get down to around thirty feet, the ground temperature takes on a constant value equal to the average annual temperature of the area. Here in Knoxville that temperature is roughly 60 degrees F.
So instead of pumping heat out of cold winter air the geothermal heat pump moves heat out of water warmed by the ground to about 60 degrees. Similarly, in the summer the geothermal heat pump moves heat out of your living room into water cooled by the ground. Since it is moving heat over a smaller temperature difference, the geothermal heat pump does less work, and therefore uses less energy.
Before the retrofit the old system was costing about $6,200 a year to run. The new unit provides the same level of comfort for about $2,200 a year.
Blink Electric Vehicle Charging Station
Just to show that we go the extra mile, we are participating in a program to provide the public with access to electric vehicle charging stations. SACE is part of the EVProject, the largest single deployment of electric vehicles and charging infrastructure in history. As a host in the EVProject, SACE had two Blink Network charging stations installed at our facility. We use the charging stations to charge our company car, a Nissan Leaf. The charging stations are also available to the public. They are located behind the building next to the parking lot.
Solar Photovoltaic System
The latest change we’ve made to bring our building fully into the modern era is installing a bank of solar photovoltaic panels. These panels make up a ground-mounted array just off our parking lot. The good folks at Green Earth Solar here in Knoxville designed and installed this 9 kW system. All of the major components were made in the USA; the solar panels were chosen because they are made in Sharp’s Memphis, Tennessee, facility.
SACE took advantage of several public programs to help us with this project. The City of Knoxville provided assistance through the City’s Green Building and Incentive Program. We also participated in the Knox County Community Action Committee’s Housing and Energy Services Program to take advantage of a Clean Energy Technology Grant. The system also qualified for the TVA Generation Partners’ Expanded Pilot (now Green Power Providers). Being part of the Generation Partners project enables SACE to sell the production from our solar system back to the utility at 12 cents per kWh above our electric rate. Since the system is projected to generate about 12,000 kWh annually this will add up to about $2,500 per year.