Square Feet: 148,000 | Savings: 44+% on Natural Gas | 12% Electric kWh |

Recommissioning the laboratory air system led to reduced outdoor air use and downsizing the central boiler plant. Energy recovery was also added on non-lab related air handling units to further reduce the outdoor air energy demand.

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Constructed in 2001, the Donald Danforth Plant Science Center (DDPSC) is a research facility that has very precise and intensive temperature and humidity design conditions. The DDPSC hired Architectural Design Guild (ADG) and Energy Resources Group (ERG) to assist in the development of an Energy Conservation Program. The program goals were to save money through greater efficiency and more cost-effective use of assets. A recommissioning of the building laboratory air system was recommended, which led to reduced outdoor air use and downsizing the central boiler plant. Energy recovery was also added on non-lab related air handling units to further reduce the outdoor air energy demand. ERG and ADG developed budgets for these recommendations, produced design documents (including all plans and specs for bid), performed construction review and approval services, and conducted a post-construction analysis to verify utility savings.

Summary of ECMs:

• High Efficiency Boiler Upgrades
• Industrial Hot Water Upgrade
• Cooling Tower Heat Exchanger
• Lab Outside Air Recommissioning
• Airside Energy Recovery
• Variable Speed Fan Drives
• Utility Rate Reductions

To maintain a safe and healthy indoor environment for employees, laboratories require much higher outdoor air exchange rates than normal facilities. Conditioning this fresh air to comfortable indoor temperature and humidity levels is expensive. ERG optimized these exchange rates for efficiency, safety, and code compliance. An energy recovery system was also installed to recover heat from warm exhaust air streams to preheat cold outdoor air streams. By reducing the amount of outdoor air being conditioned and recovering heat from exhaust air, 17% or $72,350 was saved from annual heating costs, while 12% or $64,850 was saved from annual electric costs.

The building was originally designed with three 10,000 MBH hot water boilers (25,200 MBH output total).

ERG calculated the heating loads for the building and determined they could be met with four 2,000 MBH condensing boilers.

Replacing the existing boilers resulted in $112,000 or 44% reduction in annual natural gas use.

The large compressed air system for the DDPSC is primarily used during the winter for humidification.  Installing a small compressor allowed two 50kW compressors to be shut down during the summer.
Because the DDPSC has a high performance envelope and there is so much internal gain, some space cooling is still needed below 44°F.  When the outdoor air temperature drops below 44°F the chillers are shut down and the building’s cooling load is delivered to the cooling tower via a plate and frame heat exchanger.

An investigation of gas use at the DDPSC showed that they were not on the most appropriate gas rate structure. ERG negotiated on behalf of DDPSC with the local gas utility (Laclede Gas) to switch rates from Commercial CIII to Large Volume Transportation Sales and Service.

An investigation into the sewer bills of the DDPSC revealed they were being billed for a lot of water use that was not going to the sewer. ERG worked with the sewer district to identify the % of effluent considered “non-sewered”.  The result was a 48% reduction in the monthly sewer bill.

In 2015, the DDPSC hired ERG to do a retrospective cashflow analysis of their energy efficiency improvements. This effort demonstrated an annual average savings of $208,000 over the ten-year period. The investments became cash-flow positive in 1.75 years.