Cupertino Garage: Demand-Control Ventilation System Pays for Itself with Energy Savings
One of the greatest sources of energy consumption – and consequent operational costs – for an enclosed, commercial garage is the mechanical system that ventilates it. Ventilation can account for more than 30 percent of a property’s total, annual energy bill, consuming upwards of 400,000-kilowatt hours (kWh) per year. Some 35 percent of U.S. garages rely on “on/off” carbon-monoxide (CO) sensor systems, which activate fan motors only when increased CO levels require it. California, Oregon, and Washington have adopted stricter requirements, requiring continuous ventilation even when a CO system is in place, thereby rendering type of “on/off” ventilation strategy out of code. Other states are expected to follow suit in the next few years.
When Sand Hill Property Company built a stand-alone, 1,370-space garage in Cupertino, Calif., in 2015, they decided to invest up front in cutting-edge garage ventilation control technology. The garage’s enclosed portion required a sizable mechanical ventilation system that would consume 527,000 kWh per year – some $108,000 annually – to run on a 24/7 basis. The developer hired Nagle Energy Solutions to design and install its digital, “variable flow” demand-control ventilation (DCV) system. The system keeps garage fans running continuously, varying motor speeds based on CO concentrations in the garage. The system continuously monitors energy consumption. At its present rate, it will reduce kWh consumption and peak kW demand by 500,600 kWh and 58.6 kW, respectively. Its projected annual utility fee for ventilation is $5,400 – representing an annual cost savings of $102,600. Besides meeting the stricter energy-efficiency and health and safety standards, the system’s $117, 200 installation cost will pay for itself in just 13.7 months – and yield a $1.4 million energy savings during its 15-year lifespan.
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