Indoor Dew Point: Maintaining Thermal Comfort, Avoiding Building Damage

Condensation, moisture absorption and, subsequently, mold or organic growth are often a result of high indoor dew point combined with cool surface temperatures. For example, if a facility’s indoor dew point is above 60oF, it is possible that moisture will begin to condense on cool surfaces like ductwork, chilled water supply lines, windows, or refrigeration systems. This collection of moisture can cause damage to the building, as well as to merchandise. It can even promote organic growth over time.

In addition to the risk of moisture accumulation, ASHRAE recommends maintaining a dew point below 62 oF to meet thermal comfort for approximately 80% of occupants; a dew point of 45 oF is recommended to maintain summertime humidity comfort levels.

Monitoring Dew Point

Consider this: You are a kid in a candy store with a plethora of delicious options in front of you. You sort through the store and boil your decision down to two candy bars.

Option A: The tried and true milk chocolate bar. Nothing fancy but classically delicious.

Option B: Fluffy nougat topped with caramel and peanuts, coated in milk chocolate. An exciting snack bursting with flavor.

Did you choose Option A or Option B?

If I had to guess, you chose Option B as it gives you more variety with your purchase! Now, what if I told you that the decision you just made also can apply to thermal HVAC design and dew point monitoring principals?

Option A: A design principal of maintaining 60% relative humidity (RH).

Option B: A design principal of maintaining a 60oF dew point.

Both are similar and help maintain a healthy building, but maintaining a 60oF dew point (Option B) is inherently better and offers a more reliable risk indicator. Using 60% RH as an indicator (Option A) is unreliable as it creates needless concern when air temperature is cool. In the example below, you can see that the amount of water vapor in the air remains the same while relative humidity concentration varies depending on the temperature of the air.

Conversely, a facility manager or building owner may have a false sense of security when indoor air temperature is above normal levels because relative humidity will decrease as air temperature rises. These reasons are why dew point should be used as a threshold of concern. Dew point will not only factor in moisture content and temperature of the air but also provides a risk indicator for condensation and moisture absorption, which should be a facility manager’s primary concern.

Using Indoor Dew Point as a Risk Indicator

If you are already using indoor dew point as a risk indicator for indoor moisture activity, then continue to do so! Specifically, look to ensure that indoor dew point remains below 60 oF during cooling operations to reduce the risk of moisture absorption, condensation, and organic growth.

If you are not using indoor dew point as your risk indicator, now is the time to do so! You could be surprised to learn that measuring relative humidity alone may not be keeping your facility safe.

If you are already noticing signs of moisture accumulation, mold or organic growth, then ASHRAE recommends implementing the following HVAC factors to reduce your risk:

  • Ensure that ventilated air is dehumidified to a dew point below the indoor dew point when the building is in cooling mode.
  • Ensure that all condensation inside HVAC components is being properly drained.
  • Ensure that indoor surfaces are not cooled to temperatures below indoor dew point during occupied and unoccupied modes.
  • Keep indoor dew point low enough to ensure that condensation does not occur on cool surfaces of HVAC components, building materials, or building furnishings.
  • Ensure that humidifiers are sized, installed, and controlled properly to avoid the risk of overloading indoor air with humidity.
  • Ensure that cool HVAC and plumbing components are properly insulated to keep their surfaces about 10 oF above indoor dew point.

These simple steps — in addition to proper HVAC ventilation, indoor air monitoring, indoor air verification, and keeping an eye on seasonal changes — can help ensure that your facility is operating in a safe manner while reducing risk of mechanical damage, moisture accumulation, or organic growth.

If you would like to learn more about ways in which your indoor air environments can be improved, please reach out to us. Please complete our contact form or contact us by phone at (513) 965-7300.

COVID-19 Closures: Mitigating Damage to Unoccupied Buildings

As states across the U.S. are working to flatten the curve, many businesses are impacted by COVID-19 closures as a result of “stay at home” or “shelter in place” orders to limit human interaction and prevent the virus’s spread. Additionally, many companies across the country have opted to temporarily close facilities to prevent employees from contracting the disease. With these shutdowns, it can become increasingly difficult to determine the condition of a facility and repair any issues that could be developing while the facility is unoccupied.

COVID-19 closures of restaurants

Damage to Unoccupied Buildings

Consider these scenarios that could arise in an unoccupied facility…

  • A building in the coastal region may experience high humidity that is going unnoticed, which can in turn lead to mold growth. Imagine if the facility is a retail store; the end-result might mean thousands of dollars of damaged, unsalvageable clothing merchandise.
  • If indoor moisture levels drop too low — perhaps in a cooler climate that is shifting from winter to spring temps — it could lead to wood warping. For instance, the frames of wood windows can shrink in size, making them more difficult to open and potentially creating gaps that let in more cold, dry air.
  • Low indoor moisture can also lead to peeling or separated wallpaper, or cracked paint on plaster walls. What would you do if you come back to your facility, only to realize you need to bring in professional painting or remodeling services?
  • Think about a restaurant or bar. There may be hundreds (or thousands) of dollars of liquor or wine in stock, going untouched through the COVID-19 crisis. Corked bottles of wine are not exempt from the effects of dry indoor air. Extremely low humidity levels can slowly chip away at a cork, leaving room for air to get into the bottle and ruin the flavor. The ideal humidity level for wine storage is 60%.
  • Another thought for a restaurant facility: A humid environment allows mold growth to fester. The COVID-19 shutdowns came on suddenly for many facilities. Did kitchen staff have adequate time to scrub walk-ins, pots, and pans? Were grease traps thoroughly degreased? These are potential breeding grounds for mold during non-occupation.
  • Contemplate multi-purpose facilities, such as an apartment complex with retail or dining space on the first floor. Completely shutting down HVAC airflow to the unoccupied businesses could lead to uneven air flow and temperature throughout the larger building.

The bottom line: Scenarios like the ones above will go unnoticed and unrepaired until employees return to the facility to find the damage caused by an unoccupied month.

Preventing Facility Damage During COVID-19 Closures

While these issues may seem frightful, thankfully many state governments have kept issues like this in mind when mandating shelter-in-place orders. Seeing the value and necessity of essential services, many states are allowing skilled trades such as HVAC technicians to continue working. During quarantine, let these technicians be the eyes and ears at the facility to ensure that, when business returns, critical issues didn’t develop, delaying reopening.

In addition, this downtime can also be the ideal occasion to have technicians visit the facility to address any known issues or to perform preventive maintenance. Maybe there is a repair the facility manager has been putting off because its fix requires closing a typically busy corridor or lobby area. By addressing this work now while the facility is shut down, managers can limit future downtime, employee inconvenience, and lost profit.

And as a preventative measure for the duration of this closure or in preparation of future closures, consider installing sensors to remotely monitor a facility’s indoor air quality levels through relative humidity, temperature, building pressure, and CO2 checks. A system like Melink Corporation’s PositiV® building health monitor can remotely track and trend building health, plus send alerts to the facility owner or manager when the system detects measurements outside its set parameters. While a facility may not have this in place to combat the current COVID-19 closures, it can be installed now to prepare for future unplanned closures or even a vacation (Facility managers need a break at some point, right?!). 

How Do Seasonal Changes Affect Building Health?

As we transition from dry, cool winter months to hot, humid summer months, you may be saying to yourself, “Woohoo! Bring on the heat!” However, seasonal changes can affect building health. Specifically, the summer season can present major problems for facility managers and building owners as their buildings’ HVAC systems struggle to keep up with increasing cooling loads and extremely humid outdoor air.

Just as spring plant life sprouts, HVAC mechanical issues can pop up with warmer temperatures. Poor indoor conditions such as high indoor relative humidity, negative building pressure, CO2 buildup, or drastic temperature fluctuations are just a few examples.

Staying ahead of these issues before they become noticeable, costly problems is crucial when considering the overall health of your building and its HVAC systems.

Humidity: A Common Seasonal Issue

At various facilities, a common issue that comes with changing seasons is humidity. Specifically, humidity can be difficult to maintain at a comfortable level.

Condensation on building window, a seasonal building health issue.
Condensation in office building

In the winter, the heating mode on air handling equipment can heat or evaporate the existing moisture in the air to reduce the overall relative humidity as outdoor air is brought into the building. However, in the summer, the opposite occurs: the air handling equipment cools the building space and doesn’t heat or evaporate the moisture out of incoming air. This combination of high relative humidity and indoor dew point ultimately creates conditions that promote condensation or organic growth within the facility.

A Year-Round Solution for Indoor Building Health

The most cost-effective solution to verifying and ensuring long-term indoor building health is with a sensor capable of measuring key building health metrics like differential pressure, relative humidity, dew point, temperature, and CO2.

Components of building health

By gathering data on these building health metrics, the facility manager, operator, and/or building owner can quickly verify on-site conditions in real-time, while also gaining peace of mind in knowing their buildings are meeting engineering specifications per design as seasons change. In addition to these benefits, sensors’ data gathering gives users the ability to track and trend building health over a long-term period.

Using Data to Plan for Seasonal Building Health Changes

Getting and staying ahead of maintenance doesn’t need to start with expensive truck rolls and frequent site visits. Instead, sensor solutions provide an inexpensive, effective avenue to implement a proactive mindset. The collected data can be aggregated to an easy-to-use online portal capable of summarizing, visualizing, and diagnosing issues on site, while also granting users the ability to trend and predict HVAC performance for a lasting solution.

Get ahead of the changing seasons by verifying your building is healthy today!

When Should My Building Be Balanced?

A proper air balance within a building is an important factor for providing a healthy and comfortable indoor environment for occupants.  Like many other critical building systems, the air balance must be maintained over time, and isn’t something that you can simply “set and forget”.  So then, when should a building be balanced?  Here are some common events that would trigger the need to perform an air balance.

New Construction:

Every building that has some form of HVAC system (heating, ventilation, and air conditioning) should be balanced when it is first constructed. By this, I mean that the HVAC systems should be inspected, tested, and adjusted to ensure that they are operating correctly, efficiently, and as intended by the design engineer and as expected by the building owner. A balanced building will provide a comfortable and healthy indoor environment for the occupants, delivered in an energy efficient manner, and will have a proper positive pressure. Select a TAB professional to perform the air balance who is objective, meaning that they are hired directly by the building owner and are independent of the installing contractors and equipment manufacturers, who is experienced in your particular type of building and HVAC systems, and who is certified by an industry-recognized accrediting agency, like NEBB or AABC.

Remodel:

The building should be rebalanced during any major remodel event, such as expanding the building or changing the functional use of a space within the building. This is important because the HVAC system was originally designed and balanced for specific use conditions, and when those conditions change, the system will need to be readjusted. Be sure to consult with your mechanical design engineer prior to the remodel to verify that the existing HVAC system can handle the new demands. The building should also be rebalanced anytime elements of the HVAC system are modified or replaced, such as when ductwork is rerouted or when aged equipment is upgraded. This is important for verifying that the new equipment is installed correctly, operates properly, and is adjusted for the design conditions. For a building that has cooking operations, it is important to also rebalance whenever the cooking appliances are relocated or replaced with equipment of different use or heat load, such as replacing an oven with a fryer. This is significant because a kitchen ventilation system is designed for a specific bank of appliances. When the appliances and cooking operations change, the ventilation system will need to be adjusted to ensure it correctly captures and contains the heat and effluent produced.

Periodic Tune-up:

Even if a building has been balanced during the original construction, and it is not undergoing any remodels or equipment replacements, it should still be rebalanced periodically. This is because the performance of the HVAC system can change over time due to normal use and wear and also due to adjustments made by operations and maintenance personnel. Examples of this are when an operator switches the fan mode of the thermostats from ON to AUTO or when a service technician closes the outside air dampers in a rooftop unit in an attempt to fix a comfort complaint. For the complete building HVAC system, I would recommend a proactive rebalance frequency of every two to three years. This will ensure that the systems operate effectively and efficiently throughout their lifecycle and will help prevent the very costly issues created by having a building out of balance for a prolonged period of time.

Want to understand more about air balances? Read about air balance basics for existing facilities, watch our video on how an air balance works, or contact us to learn more!

The 3 Most Common HVAC Problems During Winter

To quote a critically acclaimed HBO television series, “winter is coming, and we know what’s coming with it.” While it may not be as bad as the army of the dead, we can expect winter to bring about a variety of HVAC issues that can cost more pennies than shivers. Here are the top three most preventable winter mishaps, and how they can be avoided with a little DIY maintenance.

  1. Frozen Pipes

Besides fire, a building’s biggest enemy is water. Only this time of year, unwelcomed water doesn’t come in the form of humidity or a leaky roof, rather, in the form of solid icy pipes. Many building owners will try to cut costs by not heating their buildings at all times while completely unaware that above ceiling and sub-floor spaces can fall below zero in extreme cold weather. These spaces are home to water pipes that can freeze and burst causing un-flushable toilets, compromised showers, inaccessible tap water, and not mention, outrageous repair costs. The residual heat from the livable spaces above or below these pipes help to keep temperatures above freezing, so setting the thermostat to at least 65 °F throughout the day and night should keep the water flowing. In addition, be particularly aware of areas that are unheated or are constantly exposed to the elements like garages, loading docks, and basement storage rooms. Insulated pipes and walls will help to seal the deal.

  1. Uneven Airflow and Temperatures

Depending on the season, air is circulated throughout a building in different ways. Cold air falls which is why in the summer months, closing floor vents to allow more air to diffuse from ceiling vents is most effective in cooling a space. The opposite is true in the winter months where rising warm air is best circulated from floor diffusers and baseboard radiators. Knowing these trivial properties about air temperature can best optimize how your building is heated or cooled, so let the cool air fall and the warm air rise!

  1. Dirty Furnace Filters

While problems that arise from dirty or clogged filters are not unique to the winter, it’s still one of the most common culprits for defective air conditioning. A unit’s air filter removes particulates from the pre-conditioned air and allows the clean air to be conditioned and distributed. If a filter is clogged, airflow is reduced, and the terminal units will have to run longer to achieve desirable space temperatures. In the colder months, the air becomes dry which can dehydrate a person’s skin as a result. With dead skin cells making up 70 to 80 percent of dust content, it’s no wonder that the winter sees some pretty dirty filters. Changing an air filter is one of the easiest, cheapest, and most effective way to ensure maximum heating outputs which is why new filters should be installed before every season.

These winter mishaps are snow laughing matter, but just like bad puns, they’re easy to spot. Keeping these three common maintenance issues in mind will allow you to brave the cold and keep cozy all winter long.

What causes poor Indoor Air Quality?

Indoor Air Quality (IAQ), or the condition of the air inside a building, is a very important building health attribute that can affect the comfort, productivity, and wellness of a facility’s occupants, workers, students, and visitors.

Poor IAQ has been linked to several symptoms such as headaches, fatigue, trouble concentrating, and dizziness, as well as irritation of the eyes, nose, throat, and lungs.  The more prolonged the exposure, the greater the effect.  Here are five common factors that contribute to poor IAQ:

Negative Building Pressure – A negative building, one in which the pressure inside is less than the pressure outside, will draw air through doors, windows, and any other openings in the exterior.  This air is unfiltered and unconditioned, so whatever is outside comes inside, including high humidity, pollutants, insects, and so on.

Inadequate Fresh Air Ventilation – Fresh outside air is introduced into a building through a series of fans and dampers. Relief air is also evacuated from a building in a similar manner. These air systems must be properly set up and adjusted for the correct amount of fresh air needed for the building based on its use and occupancy.

Insufficient Contaminant Capture – Contaminants that are produced from various operations within a building, such as heat and smoke from cooking, steam from dishwashing, or pollutants from work processes, are captured and contained with systems of fans and canopies.  These systems must be properly configured and adjusted for each unique process in order to capture and contain the effluent produced.

Improper Air Distribution – The various spaces within a building have their own ventilation and pressurization needs, so the air movement inside a building is vital.  The air distribution systems must be properly configured and adjusted throughout the entire building.

Deficient HVAC Maintenance – The various fans, dampers, filters, coils, and other devices comprising a Heating, Ventilating, and Air Conditioning (HVAC) system must be cared for, and maintained correctly and frequently in order to support proper indoor air quality.

3 Steps to Troubleshooting Your Facility’s HVAC With Onsite Staff

Have you identified that your facility is experiencing a potential air balance problem?  You might be experiencing doors that are hard to open, uncomfortable temperatures, poor smoke capture, odors, drafty areas, or any combination of the other common sick building symptoms.  The inevitable question at this stage is, “Who is best to resolve this?” Bringing in your facility’s mechanical contractor may be your first instinct, but troubleshooting with your onsite managers is actually the best place to start. Work through the following questions with your facility’s day-to-day manager:  

1.  Is the equipment running?

As basic as this may come across, it is absolutely crucial to check if all HVAC equipment is operating. Check all grilles to see if air is being blown out or sucked in. Check the equipment on the roof, can you hear the fans from the RTU, MUA, or EF units spinning? Have the manager record and communicate findings.

2.  Check the thermostats

Navigate to the wall mounted thermostats and ensure that they have the proper set points. Often, a thermostat is installed and connected to the system and then left alone. When this occurs the thermostat is left at factory settings which is often set at a random temperature, maybe even 100 degrees Fahrenheit!  Your staff should be able to follow the directions on this thermostat to program it for the desired temperatures.  As well, check the thermostats for “Fan ON.”

Thermostat

3.  Check the Circuit Breakers

Check your indoor and outdoor circuit breakers. Observe if any of them have tripped or been switched to “Off.” DO NOT flip the breaker back on. If it is tripped or left off, there is likely a reason for it and you don’t want to risk frying the electrical systems. We recommend calling an electrician for this type of deficiency.

 

Armed with your findings from these simple tests, you may have been able to save some money with a Do-It-Yourself fix.  It’s possible that the journey back to a healthy building ends here.  But if the problem persists, it’s time for the level of technical know-how. Call the mechanical contractor. With your observations to these preliminary steps above, you can approach your mechanical contractor with information that will help them to better understand your situation and get you closer to achieving a healthy building.

Top 5 Reasons we get called for an HVAC Test & Balance

An “air balance” is a process for measuring the performance of an HVAC system, and for providing the occupants with a comfortably conditioned space according to design specifications. In other words, it is an overall health check for your HVAC systems to make sure the equipment is mechanically sound, that there is positive building pressure and that the thermostat and air flow are adjusted properly.  –Greg DuChane, Trane

A test and balance service serves the same purpose as changing the oil in a car to keep the engine running healthily.  Preventative maintenance for any vehicle or piece of equipment is understandably a best practice for avoiding high stress circumstances, such as a car break-down in the middle of a deserted road.  In the context of HVAC, a high stress circumstance could be losing your air conditioning on a hot August day and watching customers leave the building!  See our top 5 reasons we get from customers who call for us to come out and balance their stores:

To learn more and see pictures of many of these circumstances, read HVAC Test & Balance: Defined with Examples from the Field