ORNL Office Building 3156
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GENERAL INFORMATION
QUICK FACTS
| Location: | Oak Ridge, TN |
| Building Type: |
|
| Conditioned Floor Area: | 6,085 m2 |
| (Total Floor Area: 645 m2) | |
PROJECT INFORMATION
| Project Full Name | Oak Ridge National Laboratory Office Building 3156 |
This project was conceived to demonstrate that existing office buildings can be retrofit to significantly reduce energy intensity and reliance on fossil fuel-generated energy. Through a combination of energy efficiency renovations, renewable energy utilization, and consumption monitoring features, Building 3156 has achieved Net Zero Energy Building status. The existing office building was retrofit with minimal disruption to occupants. The energy efficiency improvements reduced the building's annual energy consumption by approximately 35% - from roughly 100 MWh/yr to 65 MWh/yr. A new solar photovoltaic power array was installed that supplies more electrical power than needed to meet the building's reduced demand.
| Project Owner: | U.S. Department of Energy (DOE) |
| Owner Type: | Federal government |
LOCATION & CLIMATE
| City: | Oak Ridge |
| State / Province: | TN |
| Site context/setting: | Rural |
| Climate Region: | 4A: Mixed - Humid |
OCCUPANCY
| Typical Number of Permanent Occupants: | 31 |
| Owner Occupied: | Yes |
| Owner Type: | Federal government |
| Average Hours Per Permanent Occupant: | 40 |
| Typical Number of Visitors Per Week: | 20 |
| Details About Occupancy: | The building contains 23 offices and a conference room. |
VISITS & GUIDED TOURS
Visiting
It is possible to visit this project
Visiting Details:
Requires prearrangements for visitors pass. See point of contact.
Touring
It is possible to tour this project
Tour Details:
Requires prearrangements for visitors pass. See point of contact.
BUILDING DETAILS
SCOPE
GENERAL FLOOR AREA
TEMPERATURE CONTROLLED FLOOR AREA
BUILDING
COMPLETION
DATE OF
OCCUPANCY/COMPLETION
COMPLETION NOTES
A new 51 kW solar photovoltaic power array was completed in October 2008. Energy efficiency rennovations include replacement of packaged terminal air conditioners with high efficiency packaged terminal heat pumps in May 2009, replacement of T12 fluoresent lighting using magnetic ballasts with T8 high efficiency lighting using electronic ballasts, installation of occupancy sensors to reduce lighting and HVAC loads during unoccupied periods. The final stage was installation of a system to provide monitoring of power usage down to the individual circuit levels, completed September 2009.
ARCHITECTURAL DETAILS
INDOOR ENVIRONMENT QUALITY
INDOOR ENVIRONMENT
Each room is equipped with a Packaged Terminal Heat Pump (PTHP) that allows individual control of air temperature. Although the units are automatically controlled based on space occupancy, zones within the building are continuously monitored for air temperature and relative humidity. When an air temperature or relative humidity set point limit is reached, the PTHPs in that zone are automatically switched on. This prevents damage to the building and its contents by limiting temperature and humidity swings, while minimizing energy consumption for HVAC during unoccupied periods.
Each office is provided with an operable window to provide occupants with a means for outside ventilation during mild weather.
INDOOR ENVIRONMENT STRATEGIES SECTION
- Maintain relative humidity levels between 30% and 60%
- Provide occupants with the means to control temperature in their area
- Provide occupants with access to operable windows
DESIGN
DESIGN PROCESS
PreDesign:
Building 3156 was chosen for this pilot project because it is representative of a typical small office building that can be readily retrofit with energy efficiency improvements at a reasonable cost to realize substantial reductions in energy consumption, and a reasonable payback period. One of the team's goals was to design energy efficiency renovations that could be implemented with minimal disruption of building occupants. Building 3156 is new enough (built in 1994) that the building envelope is reasonably well insulated with minimal air leakage. Therefore, major demolition that would be required to seal and insulate the building shell would not be necessary.
The team determined that renewable energy should be used to supply the building's entire reduced energy demand after the energy efficiency renovations were completed. It was acknowledged that at current prices, an attractive payback period for renewable energy options might not be achievable. However, use of renewable energy would demonstrate the technical feasibility and will certainly become more cost effective in the future.
Design:
The most prominent feature of the project is the 68 MWh/yr solar photovoltaic power array. The project team determined early in the design process that solar photovoltaics offered the most practical source of renewable energy for the project. The solar array procurement was awarded based on competitive bidding.
The project team determined that energy efficiency renovations should be based on proven commercially available technologies to demonstrate that significant energy intensity reductions can be realized by owners of existing buildings with minimum financial risk. The team elected to include highly efficient packaged terminal heat pumps, high efficacy T8 fluorescent lighting with electronic ballasts, HVAC and lighting control through occupancy sensors, and improvements in managing power demands of computing resources in the project.
The project team determined that a means is required to monitor energy use profiles within the building so that potentially wasteful loads can be better understood and controlled, and so that projected energy savings can be reliably verified. A proprietary building management system was selected to provide this service. In addition to real-time monitoring and control, the system stores usage data for individual circuits as well as clusters of circuits supporting like loads.
Construction Process:
One of the project team's criteria was to minimize impacts on building occupants. The solar array was erected outside the building perimeter along the access road. There was no impact to the building occupants.
Work that would potentially disturb occupants, such as installation of PTHPs and work that required power outages, was scheduled during off hours.
Measurement:
Output of the solar photovoltaic power array is monitored to quantify performance and confirm that it supplies the building's energy demand.
Energy consumption data is monitored and collected to verify the effectiveness of energy efficiency renovations and to identify unexpected loads. This provides a tool to find ways to further reduce energy consumption, and to readily identify new loads that could hamper the attainment of energy reduction goals.
LESSONS LEARNED
The project goals were: 1. to beat the Energy Indepence and Security Act 2003 baseline, which is to reduce building energy intensity 30% by 2015; and 2. to achieve at least net zero energy consumption. These goals were met as as a result of the retrofit measures that were taken as previously described.
An important lesson learned is the necessity of integrating the various stakeholders involved in building operations such as the occupants, facility management, IT, and maintenance organiztions to ensure that critcal priorites are met during retrofit implementation.
FINANCES
GENERAL INFORMATION
The project was financed by ORNL operating funds.
PROJECT COSTS
SOFT COSTS
HARD COSTS
ACQUISITION COSTS
FINANCE DETAILS
The majority of the project cost is for the solar array. It is acknowleged that at today's costs, the solar photovoltaic power technology does not offer an attractive payback period without substantial incentives. However, it is expected that costs for solar technology will continue to decrease and will be competitive sometime in the future. The selection of the solar array was not based on payback.
The energy conservation measures that were selected do offer good payback potential in the short term. The HVAC units were near the end of their service lives, and would have needed to be replaced in the near future. The incremental cost of upgrading from standard air conditioning units with resistance heat to heat pump units was minimal. The calculated payback period for the upgrade is 2.6 years.
The payback potential of upgrading from T12 fluorscent lighting using magnetic ballasts to T8 lighting with electronic ballasts is well known.
The largest single energy savings is from controlling loads through occupancy sensors (including de-energizing HVAC units during unoccupied periods). The costs for installation were minimal and payback will be realized in short order.
GENERAL ENERGY
GENERAL INFORMATION
The intent of this project was to transform the existing office building into a Net Zero Energy Building. The renewable energy source chosen for the project is a 51 kW solar photovoltaic array which is tied into the local grid and generates power in excess of the annual demand.
The key to meeting the net zero goal was reducing the building's energy demand to a level that could be met with a reasonably-sized solar array. The historical annual energy consumption for the building was roughly 100 MWh/yr, and the project team established the reduced energy consumption target to below 60 MWh/yr. The actual energy use data extrapolated based on an eQuest model predicts annual energy consumption to be 65 MWh/yr--occupancy is 24% higher than modeled. The solar array is expected to produce 68 MWh/yr, resulting in a surplus of 3 MWh/yr.
The project team determined that the energy conservation renovations would be designed to minimize disturbance of the building's occupants. Additionally, the energy savings means would use existing and proven equipment and technologies that are readily available on the market. Thus, candidate energy savings proposals were screened to these criteria. The selected energy savings technologies were:
- Roof insulation was increased from R-5 to R-23 and a high-performance reflective membrane was added.
- Existing HVAC units were replaced with high efficiency heat pumps. The pre-existing HVAC consisted of packaged through-the-wall terminal air conditioners with electric resistance heating. These units were replaced with high efficiency (EER 11.5) packaged terminal heat pumps (PTHP). The units feature flexible control configuration settings to allow fine tuning of energy conservation settings.
- The building was originally equipped with standard T12 fluorescent lighting and magnetic ballasts. The lighting system was upgraded to high-efficacy T8 fluorescent lighting and high-efficiency electronic ballasts. In addition to direct energy savings, the new lighting system requires much less maintenance.
- Occupancy sensors were installed to shutdown certain "amenity" loads when spaces are unoccupied for a specified period. When an office is unoccupied, the HVAC and lighting circuits to that office are de-energized. Likewise, the lights and vent fans in the restrooms operate only during occupancy and a short period following. Some minimal HVAC is required even during unoccupied periods as needed to prevent freezing and to maintain relative humidity levels below levels that would promote fungal growth. Satellite temperature and humidity sensors were placed in zones throughout the building. When a temperature or humidity set point limit is crossed, the PTHPs in that zone are re-energized to maintain acceptable environmental conditions even though the areas may be unoccupied.
- Computing resources comprise a significant portion of a modern office's overall energy demand. The team concluded that several opportunities existed for significant energy savings with computing resources.
- Prior to the renovations, nearly every office had its own (or multiple) printer. A high-volume central printer was installed on each floor to eliminate the need for numerous printers.
- Standby loads of personal computers while not in use represented a considerable energy drain. It is laboratory policy to leave computers on 24/7 so that updates can be pushed during off hours. To improve the situation, the team selected a software package that puts the computers into a low power standby state during off hours. A quick keystroke is all that is required to wake the computer when the user returns to work. In the meantime, computers can be "awakened" remotely by the IT staff for software updates. These measures resulted in a 40% decrease in nighttime plug loads.
- "Smart Power Strips" were installed in each office to reduce "miscellaneous energy loads" (MELs). If a computer is not being used in an office, it can be assumed that certain other loads are not needed. The Smart Power Strip senses when the connected computer is in use. When the computer is in standby or sleep status, the other outlets on the power strip are automatically de-energized.
- In order to better understand energy use profiles and validate the results of the energy savings strategies, a means was needed to monitor energy usage. A system was installed to provide such monitoring. The building is individually sub-metered. Current transformers were installed on each circuit in the facility and connected to individual circuit monitors. In addition, circuit monitors for groups of like-type loads (e.g., HVAC, lighting, receptacles) were clustered. All of this real-time and historical data is available online from authorized PCs. This provides an invaluable tool for validating the results of the energy savings measures and monitoring and tracking down "suspect" loads.
ENERGY DATASETS
| Dataset Name | Year | Is Default | Type | Purchased Energy (kBtu/ft²) | |
|---|---|---|---|---|---|
| eQuest model | 2009 | No | Actual & simulation hybrid | -1.47 |
SITE INFORMATION
GENERAL INFORMATION
- Previously developed land
LAND USE STRATEGIES
SITE STRATEGIES
WATER
WATER STRATEGIES
- Select plants for drought tolerance
- Use mulch to improve water retention