4 FM quick reads on HVAC
1. Proper Maintenance Will Improve Air Distribution Efficiency
One way to improve the efficiency of the air distribution system is to make sure that components are operating properly, says the U.S. Environmental Protection Agency’s Energy Star program. For example, when systems have pneumatic controls, the thermostats require recalibration on a regular basis – typically once or twice a year. That sort of preventive maintenance is a better strategy than waiting for complaints from occupants who are too hot or too cold.
Zone dampers are another potential trouble spot. Facility staff should regularly inspect the damper, linkage, and actuator for to ensure they’re operating properly. In systems in older buildings haven’t been carefully maintained, there’s a good chance of having some zone dampers frozen in one position. Tackling that problem can be an expensive and lengthy process, especially in big buildings. Consider allocating a portion of the annual maintenance budget for this purpose to address a certain quantity or percentage of zones. For example, in a 100,000-square-foot, 10-story office building with 150 VAV zones, the maintenance budget might include time and money to evaluate 50 VAV zones per year.
Steps like these can not only reduce energy use, but also improve occupant comfort.
2. Evaluate How the BAS Will Connect With Other Systems
A building automation system does not exist in a vacuum. When deciding whether to install a new building automation system, it’s important to look at other building systems as well. For example, to take full advantage of the building automation system, the system will have to connect to HVAC systems. So check the controls on HVAC systems to ensure that they have the capabilities needed.
As with any powerful software system, it is essential to consider how information will be provided to a building automation system. Many facilities already have some form of building automation system. If that’s true, the facility executive will have to determine how useful maintenance and operation information will be transferred from the old system to the new one. In the best case, it will be possible to import the data automatically from the old system. Talk to the building automation system vendor to determine if it’s feasible to do that. The other route is manual data entry.
3. When Sizing HVAC Systems, Focus on Proper Margin for Safety
When the HVAC system is being designed, one important decision is how big equipment needs to be. Peak demand on very cold and very hot days is one important consideration. And flexibility for change in use of a space may be another element in the decision.
Of course, there’s a price to be paid for extra capacity, and it’s not just the higher first cost of larger units. Operating expenses are likely to rise for equipment operating at part load. What’s more, larger units may very well be noisier. Properly sized units, by contrast, will likely run better, be more energy efficient and have fewer maintenance problems.
Clearly it’s important not to oversize units. But there’s evidence that does happen in some cases. One possible source of trouble is industry rules of thumb for determining occupancy when occupancy isn’t known. Those rules of thumb may lead to an overestimation of loads. Another potential problem is building in too large a margin for so-called design days, when temperatures are at their highest and lowest, so that designers have a cushion — just in case.
For facility executives, the way to avoid oversizing is to work closely with the design team to ensure that the system can handle the loads it will be facing, with an appropriate margin for safety — but not an excessive margin.
4. Keep the Unintended Consequences in Mind When Cutting Costs
In today’s economy, the pressure to cut costs is intense. But cost cutting moves can backfire if consequences aren’t carefully evaluated.
Value engineering is a prime example. Changes made to reduce construction costs can increase other costs. Buying windows that are less energy efficient, for example, will not only raise energy costs, but also push the HVAC system perilously close to capacity on design days.
Higher energy prices aren’t the only risk. Design changes can affect compliance with fire safety code or inadvertently compromise security.
In a worst case, a move to cut costs could actually cost a company business. In one case, a financial firm identified a new location that had lower rental rates and was closer to home for most employees. It came close to signing the new lease, but eventually decided to stay where it was. The reason: The current location was very close to a major customer, one that was likely to be a significant source of new business in the future. The real estate savings were no reason to risk that opportunity.
It’s important to solicit input from all parties that will be affected by cost cutting moves. Doing that makes cost cutting more difficult – the parties affected are likely to put up at least a little bit of a battle – but it can save money in the long term.
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