Rainwater harvesting is the process of collecting rainwater to supplement non-potable water requirements. This can be very beneficial for commercial facilities, especially when combined with HVAC applications. Cooling can account for up to 40% of a building’s utility budget. Water consumption in a 200,000 sq. ft. building, can run up to 2 or 3 million gallons annually. Harnessing “free” water for a cooling tower is simply smart business and fortunately, the cooling season is typically the rainiest. Roughly 0.62 gallons of water can be gathered for every sq. ft. of collection surface. This presents an excellent opportunity to go green while lowering energy costs.
How Does it Work?
Rainwater harvesting systems collect water from the roof and redirect it to a storage tank. The water can then be utilized for a host of purposes, from irrigation to cooling tower makeup. Rainwater is soft with nearly no dissolved solids. This allows the water to be recirculated many times before it must be flushed out, a process which can discharge hundreds of gallons of water at a time. It is also relatively pure, and can therefore be utilized with less treatment than water from other collection surfaces. It will still require the addition of biocides to minimize algae growth, yet even these will not need to be replenished as often when the water is being re-circulated.For facilities where the demand will be greater than the supply of rainwater, it is possible to add additional sources, such as parking lot storm water, collected in underground cisterns, or treated grey water, which we have addressed in-depth in a previous blog (click here for “grey water recycling”).
Benefits of Rainwater Harvesting:
- Saves drinking water that would otherwise be evaporated
- Lowers utility expenses
- Reduces the amount of water utilized in the process to flush out the tower water
- Minimizes chemical treatment costs
- Conserves resources and demonstrates commitment to sustainability
- Can be helpful to achieve LEED certification
- Building Automation Systems (BAS) can be incorporated for monitoring and control of collection conditions and system operation
Rainwater Harvesting in Practical Application
If sustainability and operational budgets are a concern for the owners of your next project, contact a member of the BCH estimation team. We can provide you with innovative solutions for both HVAC and plumbing.
BCH Mechanical has been a trusted name in Florida construction since 1976, delivering innovative design, high quality craftsmanship and excellent customer service. BCH capabilities include HVAC, plumbing, medical gas, piping, sheet metal, LEED, Design/Build, 3D-CAD/BIM coordination, and HVAC service. Visit BCH on the web: www.bchmechanical.com.