Parking Garage HVAC Upgrades Can Drive Big Savings
Many energy managers and building owners are missing a source of big HVAC savings. In time, it is a savings most will enjoy, since the equipment necessary to achieve the savings is the only feasible means of complying with toughening regulations. That’s a big driver–but there is an even bigger one: Putting the new systems in place can prvent people from getting ill.
All this action is taking place in parking structures.
Frank Nagle, the Founder and Principal of Nagle Energy Solutions, provided statistics on four California properties NES retrofit with new fan control systems. The claims are startling. The Parc Pointe Apartments in Burbank is representative. Nagle reported a 40 percent reduction in kWh as a percentage of the property’s total annual energy consumption. The kWh spent on the garage facility itself was reduced by 94 percent. The total project cost was $69,774, which was reduced by a utility rebate of $15,494. That brought the total cost to $54,280. The annual energy savings was $45,300 and the payback period on the installation was 1.5 years, according to Nagle. The averages for the other properties were similar, according to Nagle’s numbers.
The bottom line is that there is a lot of low hanging fruit in parking garage HVAC. “It has become a common understanding that the greatest source of energy use in commercial garages is lighting,” Nagle said. “I have the numbers to prove that is very wrong. Typically it is two-thirds [to] one-third. If you are running the garage fans the way you should, according to code, that’s the bigger source of energy consumption in the garage.”
The savings is made possible by a quantum change in sensor management and control of ventilation fans. There are several problems in the traditional manner in which carbon monoxide sensors systems work, Nagle said. The first is pretty basic: They often only seem to be doing their job. Sensors spaced throughout the structure are intended to send an alarm when the carbon monoxide level exceeds a certain level. Often, however, the sensors dry out – becoming inoperative — or “drift” to the point that they are not accurately reporting what is in the air. The regulations mandate that sensors must be recalibrated, otherwise fixed or replaced. This doesn’t happen as regularly as it should. Indeed, in many cases the facility manager may not even know that there is a problem.
A second major problem is that the use of fixed speed drives means that motors are either on or off. This real world impact of this binary choice is that either a tremendous amounts of money is spent running the motors whether there is reason to or not or the motors are kept off and the levels of carbon monoxide rise beyond the limits. The latter choice often is taken.
In Nagle’s system, the traditional approach – an on/off motor linked to uncommunicative sensors – are changed in two ways. The motor is retrofitted with a variable speed drive. This allows the motor to exert only the energy necessary to keep the air flow at required levels. The new rules mandate communications between the sensor and the controller to ensure that the former is operational. Nagle says that his system’s sequencing and programming goes beyond baseline code requirements and makes the 90-plus percent energy reduction possible.
The challenge will get worse under new regulations. In 2014, California, Oregon and Washington toughened the rules concerning the level of ventilation necessary in a parking structure. For instance, in California new levels mandated in Title 24 are a minimum airflow of .15 cubic feet per minute (CFM) and a maximum of .75 CFM. This means that an air flow must be maintained for all the times a building is considered occupied (this differs between residential and commercial properties). Thus, the a fixed speed drive motor must run continually. The cost of meeting this requirement is prohibitive, Nagle said. A motor driven by variable speed drive, however, could ramp up and down as necessary. Nagle said that other states and individual municipalities are making their codes stronger. Changes, he said, are moving roughly west to east.
Of course, NES — which is headquartered in Menlo Park, CA — is not the only company in the business. Other companies the sector are Johnson Controls, Honeywell Analytics, Siemens, Viking Controls, Kele, Macurco and others.
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