Return to site home page

01/01/2016

Fast Fixes for Thermal Comfort

Resolve occupant complaints by improving your HVAC performance

By Jennie Morton
 

Resolve occupant complaints by improving your HVAC performance.

Workers in office

Are your employees constantly roasting or freezing? Thermal comfort can be a prickly issue for FMs when complaints seems like a distraction from more pressing operational issues.

Instead of downplaying these comments, treat them as a clue that your system’s performance is suffering. By resolving arctic blasts or muggy conditions, you can see returns on your energy bill, protect equipment longevity, and preserve worker productivity. We’ve gathered 10 practical and low-cost tips that will help you root out discomfort.

Don’t Fault the Space Heater
Thermal comfort is far more complex than the temperature reading on a thermostat. While there are individual factors at play such as personal tolerance and wardrobe choice, there are six conditions that affect the perception of warmth or coolness: “metabolic heat production (physical activity), clothing, temperature, mean radiant temperature, air velocity and air humidity – different combinations of these parameters may result in the same thermal sensation,” notes a 2012 study by REHVA, the Federation of European Heating, Ventilation and Air Conditioning Associations.

Thermal Comfort Survey

Use this tool to uncover spaces that are too hot or cold. Read More >>

Note that over 65% of an occupant’s thermal comfort is dependent on your HVAC system. Unless your company has a flexible dress code or you’re tolerant of personal fans and heaters, employees have few options to influence their microclimate without your involvement. This is a striking consideration given how much a lack of thermal comfort can undermine productivity.

Alleviating sources of workplace dissatisfaction is one of those rare times that facilities management can make a direct impact on the bottom line. A literature review by the international journal Energy and Buildings found that because employee compensation is many times higher than building operations, “there is a potential monetary gain due to improved worker productivity” when better indoor conditions are provided. The data also confirms that the “thermal indoor environment is … the most important environmental factor in office productivity.” This means temperature beats out other comfort factors like acoustics, lighting and ergonomic furniture.

“When people aren’t comfortable, they can’t focus and they will make their frustration known. No one ever says ‘I am so comfortable at work today!’” says Bud Hammer, President of Atlantic Westchester, an HVAC service firm. “But when employees are satisfied with their environment, it’s simply not a topic of conversation.”

“Happy tenants are quiet tenants,” reiterates Kevin Brown, Vice President of Engineering with ABM, a facility solutions company. “You already spend a majority of your job addressing concerns and fixing problems. Use these comfort complaints as a sign that your building is spending too much energy trying to get the job done. With a bit of understanding and a few system tweaks, you could uncover massive savings.”

So what are the ideal thermal conditions for workers? Regrettably, there isn’t a perfect setting that will eliminate distraction. Numerous studies have tested how much productivity is impacted by temperature, but the results are entirely dependent on the task at hand. For instance, employees who rely on manual dexterity, even for something as simple as typing, suffer more in colder interiors, but any teacher can tell you how listless students become on a hot and humid day. Even trying to achieve a neutral setting can also be in vain because “people often prefer to feel warmer than neutral in winter and cooler than neutral in summer,” notes a report by the World Green Building Council.

Rather than one mythical setting, aim for a range of temperatures that can be refined based on climate conditions and occupant density. For example, many municipal codes require a minimum occupied temperature of 68 degrees F. from October to April and up to 78 degrees from April to October. You can also consult ASHRAE Standard 55: Thermal Environmental Conditions for Human Occupancy, which was last updated in 2013. It offers a host of operational parameters that acknowledge the interconnectedness between air speed, temperature, humidity and occupant access to thermostat controls.

ASHRAE 55 also offers an occupant survey. This tool can be used to document overall satisfaction at a specific point in time. Brown says you can even use a simple online query tool like SurveyMonkey. Gather feedback several times a year to gain a complete sense of your thermal dynamics. The key is to make an authentic effort to address occupant needs. If you do nothing with the feedback, workers will think you’re just trying to placate them without taking their concerns seriously. Legitimize complaints by looking for patterns of discomfort and genuinely trying to get to the root of the problem, advises Hammer.

Consider how your envelope affects thermal comfort. Those sitting near exterior walls are more likely to feel drafts as heat is drawn out of the building. Windows could be double trouble if they're unglazed, leaky, or single panes.

Take Your Building Systems to Task
If your occupant survey indicates there’s a persistent issue, it’s time to look into system performance.

“On a typical building, the biggest factors that affect thermal comfort are the air conditioning system itself,” Brown notes. “Look at air speed, moisture level and air temperature to figure out what’s going on.”

Draftiness is a common complaint and can be caused by incorrect pressurization, leaky windows or too much air blowing out of a ceiling grille, says Hammer. As heat is lost through the envelope, someone sitting near an exterior wall may feel an uncomfortable current of air as the heat is drawn out of the building. Humidity, which comes from excess moisture, can alternately create a stuffy, suffocating atmosphere or a cold and clammy one.

Returns that are too high can also be a culprit, Hammer adds. Tall ceilings may be trendy, but remember that warm air rises – if the grille or register is too far above individuals, the heated air may never reach them in the first place. Conversely, not having enough diffusers could be the problem. This is often the case when there has been a major fit-out or remodel, explains Brown. The original HVAC design may no longer be able to support the new layout and its accompanying heat load.

If you use a VAV system, flimsy ductwork may be to blame. “Flexible ducts are generally acceptable 6-8 feet past the VAV box, but we often uncover runs of 20-30 feet,” says Brown. “Use rigid ductwork at these lengths to ensure pressure isn’t lost.”

PageBreak

Lastly, oversized equipment could be at the heart of the issue, Hammer observes. Many systems have been designed to make the building comfortable against the hottest and coldest conditions. But these only represent a handful of days each year, not your average thermal needs.

10 Fixes to Create a Happy Balance
Once you’ve identified how your building systems are falling short of thermal expectations, start with budget-friendly tweaks and work your way up to full replacements or redesigns if necessary. Try one of these 10 areas to secure improved comfort.

1)    Perform Basic Maintenance. Keeping up with preventive maintenance? Don’t let general upkeep fall behind. “You wouldn’t own a Bentley and have the cheapest mechanic work on it,” says Hammer. “If it’s not done correctly, HVAC can cost a lot of money in terms of asset depreciation, equipment degradation and energy inefficiency.”

2)    Install a Programmable Thermostat. Hammer suggests taking away temperature adjustments from occupants, particularly as they aren’t responsible for the energy bills. If a lock seems too dramatic, use a thermostat that can only be changed within a few degrees. This gives workers a reasonable amount of control but prevents the settings from getting out of hand.

3)    Look for Leaks. Are you positive that enough air flow is reaching occupied spaces? “Have a testing and balancing company review your system,” Brown recommends. “They will measure the air flow at the diffusers and compare it to what the fans are generating, looking for leakage between the two.” You might be able to resolve leaks by sealing up gaps in the ducts with a polymer, he adds.

4)    Evaluate Fan Speed. Is too much air coming out of your ductwork? Is it too noisy? If the fan is running too fast or there’s not enough distribution outlets, air velocity may be excessive and noise is distracting to occupants, Hammer explains. To remedy the issue, adjust the fan or add extra outlets.

5)    Use Automation. “A smarter system is a better system,” Brown says. “You’ll gain functionalitysuch as trending, automated scheduling and remote control.” Many dashboards can send alerts when a system’s operation has moved beyond the set points or there’s a failure, adds Hammer. This responsiveness will allow you to quickly resolve systematic issues that might otherwise go unnoticed without monitoring.

6)    Expand Control Points. Speaking of monitoring, how much insight do you have into your equipment performance? “Don’t cut any of your controls budget,” stresses Brown. Additionally, there are a host of data loggers and sensors that will measure temperature and humidity patterns, says Hammer. Compare the data to weather conditions to identify comfort disparities.

7)    Retrofit Windows. Upgrade single pane windows to double pane for added thermal resistance, advises Brown. Otherwise, a solar film can help reflect glare. Be mindful, however, of how much reflection you choose if some of that natural heat is needed in the winter.

8)    Tighten the Envelope. Target air infiltration between exterior walls and the roof. As an added benefit, you’ll reduce mold risk as moisture is using the same path to enter your building, Brown notes.

9)    Add Radiant Floor Heating. If you have a major renovation underfoot, consider a radiant heat system. They come with a higher upfront cost but are more effective at achieving comfort than conventional HVAC, Hammer says. They also afford the opportunity to create zones.

10)    Commission Continuously. Use ongoing commissioning on an annual basis or every 2-3 years, Brown stresses. This is especially important if you’ve added controls –
you want to confirm that measurements are accurate and schedules are followed.

As you make changes to improve thermal comfort, keep occupants in the loop. “HVAC is often a mystery to them as it’s hidden behind walls, above the ceiling, in the basement, or on the roof,” says Hammer. “Help them understand how you are working to make their space comfortable, efficient, and satisfactory.”

Jennie Morton jennie.morton@buildings.com is Senior Editor of BUILDINGS.