Skip to main content

Top 5 Air Distribution Issues in Commercial Office Buildings (And How to Fix Them)

Walk through any Nashville office building in July, and you’ll find a familiar scene: one department wearing sweaters while another three doors down is sweating. Poor air distribution doesn’t just create uncomfortable employees, it drives up utility bills, accelerates equipment wear, and generates endless tenant complaints.

Understanding Commercial Air Distribution Systems

Your commercial HVAC system must deliver conditioned air uniformly throughout your building, then return it efficiently for reconditioning. A proper distribution system balances supply air delivery, return air pathways, and pressure relationships. When these elements fail, you get the hot spots and cold zones that plague Nashville office buildings.

Issue #1: Uneven Temperature Distribution

This is the problem everyone notices, some offices feel like saunas while conference rooms require jackets. Uneven distribution ruins productivity and generates endless complaints.

Causes and Symptoms

Design flaws top the list. Many Nashville office buildings were built during rapid construction where HVAC design took a back seat to speed, resulting in supply vents placed without considering office layouts, window exposure, or equipment heat loads.

Sun exposure adds complexity. South and west-facing Nashville offices absorb significant solar heat gain from intense summer sun, but the HVAC system treats them the same as shaded interior spaces.

Tenant improvements make things worse. When tenants reconfigure layouts, they rarely adjust air distribution to match. That vent that once served an open area now blows into a wall.

Solutions and Prevention

HVAC zoning strategies give you independent control over different building areas, adjusting for varying occupancy patterns and solar loads. Air balancing involves technicians measuring airflow at each vent and adjusting dampers until distribution matches specifications, essential whenever layouts change.

For persistent problems, variable air volume (VAV) systems modulate airflow to individual zones based on actual temperature needs rather than pushing constant volumes regardless of demand.

Issue #2: Blocked or Obstructed Vents

Blocked vents create surprisingly complex problems. What starts as a single obstruction cascades into pressure imbalances affecting entire floors.

Common culprits include furniture positioned under supply vents, storage accumulation near returns, renovation debris blocking ductwork, and cardboard covers employees place over “too cold” vents.

Nashville office buildings with frequent tenant turnover face this constantly. Each new tenant rearranges furniture without considering air distribution, then complains about the temperature problems they’ve created.

The fix requires immediate clearing of obstructions plus establishing tenant guidelines about maintaining clearances. Your facility services agreement should include quarterly walkthroughs checking for blocked vents before they create system-wide problems.

Issue #3: Ductwork Leaks and Damage

Hidden behind walls and above ceilings, deteriorating ductwork silently wastes energy. The U.S. Department of Energy estimates 20-30% of conditioned air escapes through duct leaks in typical commercial buildings. Nashville’s older office stock often exceeds that figure.

Where Problems Hide

Connection points between duct sections fail first as vibration and Nashville’s temperature cycling gradually loosens joints. Penetrations and takeoffs for supply vents create weak points where improperly sealed connections let air escape into ceiling voids. Physical damage from contractors working in ceiling spaces, trade work, or rodents creates additional leak points.

Detection and Repair

Modern duct leakage testing pressurizes your ductwork to measure exactly how much air escapes. Thermal imaging during operation reveals leaks by showing temperature patterns. Many commercial HVAC contractors in Nashville offer these diagnostic services.

Professional duct sealing typically pays for itself within 2-3 years through reduced energy consumption.

Issue #4: Improper System Balancing

This invisible problem drives facility managers crazy because everything appears to work fine, except temperatures never match thermostat settings, and some areas consistently run hot or cold.

System balancing involves technicians measuring airflow at every supply and return, comparing actual delivery against design specifications, then adjusting dampers to redistribute air properly.

Why buildings lose balance: Dampers gradually shift position, filters accumulate dirt changing pressure relationships, equipment degrades, and tenant modifications alter space conditioning needs. Nashville’s seasonal extremes worsen this, a building balanced for summer cooling may be completely wrong for winter heating.

The Professional Balancing Process

Proper balancing requires trained technicians with calibrated instruments documenting baseline measurements, comparing against design specifications, making systematic damper adjustments, and re-measuring until all zones meet specifications.

This typically costs $2,000-5,000 for medium sized office buildings but eliminates ongoing complaints and energy waste. Most facility managers schedule balancing every 3-5 years or after significant tenant improvements.

Issue #5: Inadequate Return Air Pathways

Supply vents get attention, but return air pathways matter just as much. Without adequate returns, conditioned air can’t circulate properly.

Closed office doors create constant problems. Without return air paths, supply vents pressurize rooms, preventing additional airflow. The room gets stuffy, and supply air backs up into the general distribution system.

Tenant improvements worsen return air issues. Converting open offices into private offices without adding returns creates isolated zones that won’t condition properly. Conference rooms suffer especially, pack 10 people in a room with minimal return capacity, and temperatures quickly become uncomfortable.

Nashville Specific Considerations

Nashville’s commercial building stock includes everything from converted warehouses to modern high-rises. Older buildings often have return pathways that made sense with original layouts but fail with modern configurations.

Nashville’s humidity requires constant air circulation to manage moisture. Restricted return pathways reduce air changes, letting humidity accumulate, creating mold complaints in below grade offices or interior conference rooms with poor air exchange.

The Hidden Costs of Poor Air Distribution

Beyond obvious discomfort, air distribution problems drain your operating budget in ways that don’t appear on HVAC service invoices.

Cost Category Impact of Poor Distribution Annual Cost (Typical 20,000 sq ft Office)
Energy Waste System runs longer to overcome distribution inefficiencies $3,500-6,000
Equipment Wear Increased runtime accelerates component failures $1,500-3,000
Employee Productivity Uncomfortable workers are less effective $15,000-25,000 (estimated)
Tenant Retention Temperature complaints drive lease nonrenewals Variable, potentially significant

Energy waste happens because systems run constantly trying to satisfy thermostats in poorly served zones. The HVAC system might maintain 72°F in well-distributed areas while running continuously to reach 72°F in problematic zones, burning energy with diminishing returns.

Employee productivity takes a measurable hit. Studies consistently show cognitive performance declines when temperatures drift outside the 68-74°F comfort range. For knowledge workers, even a 5% productivity reduction costs far more than fixing the underlying air distribution problem.

Professional Air Distribution Solutions

Fixing air distribution requires addressing root causes, not symptoms. Professional diagnostics include airflow measurements at all supply and return points, duct leakage testing, static pressure measurements, and thermal mapping showing where temperature problems occur.

These assessments often reveal surprising causes. What occupants describe as “the HVAC doesn’t work on the third floor” might be ductwork damaged during a roof repair or a damper accidentally closed during maintenance.

Modern solutions include building automation integration for continuous monitoring. For Nashville buildings dealing with seasonal variability, scheduled seasonal rebalancing optimizes distribution for both summer and winter demands.

Don’t Forget the Water Side

While air distribution gets primary attention, HVAC systems depend on plumbing infrastructure too. Chilled water and hot water distribution systems face similar challenges, leaks, corrosion, and flow restrictions that undermine HVAC performance.

A leaking chilled water line in a ceiling plenum can create humidity problems that no amount of air distribution adjustment will fix. Air trapped in hydronic heating systems creates flow restrictions causing uneven heating, another problem requiring plumbing expertise to resolve.

Take Control of Your Air Distribution

Poor air distribution doesn’t fix itself. Whether you’re dealing with tenant complaints, concerned about energy costs, or planning facility upgrades, addressing these issues delivers measurable returns in comfort, efficiency, and tenant satisfaction.

Ready to solve your office building’s air distribution challenges? Schedule a comprehensive air distribution analysis with Interstate AC. Our commercial HVAC specialists use diagnostic testing to identify exactly where your system is failing and provide lasting solutions. From system balancing to ductwork repairs and zone control upgrades, we’ll help you achieve the consistent comfort your tenants expect. Contact us today.

How To Choose the Right HVAC System for a Large Space

Maintaining a commercial building is complex, and business owners often need professional advice on how to choose the right HVAC systems for a large space.

Although every project is different, maximizing comfort, energy efficiency, and reliability for your business means looking at multiple elements.

Size Matters

The unit size is the most important consideration when selecting a cooling and heating system for your commercial space, but bigger isn’t always better.

In addition to considering the square footage of the space when trying to choose the right HVAC system for a large space, evaluate the layout, insulation, ceiling height, sun exposure, and number of people working in the space all influence the ideal unit size.

To calculate the required cooling capacity in BTUs (British thermal units), divide the square footage by 400, then multiply by 12,000 to get the minimum cooling capacity; you’ll need to add additional capacity for factors like windows, high ceilings, and workers.

Additional Factors to Consider

Climate

Not all HVAC systems work the same in every environment. Extreme temperatures in either direction can affect system efficiency and capacity.

Indoor Air Quality Needs

HVAC directly influences indoor air quality, including humidity, ventilation, and air filtration, so you need to choose a system that creates a comfortable and healthy working environment.

Energy Efficiency

The Seasonal Energy Efficiency Ratio (SEER) requirements apply to commercial systems. The higher the SEER rating, the more efficient the system and the less it will cost to run.

Regulations

In addition to SEER ratings, your HVAC system must comply with applicable government regulations.

Get Help With Commercial HVAC

When you need professional, experienced insights into how to choose the right HVAC system for a large space, get in touch with Interstate AC at (615) 802-COOL (2665).

We’re the most trusted commercial HVAC experts in Middle Tennessee and have the expertise to ensure your business stays comfortable year-round.

Frequently Asked Questions

What Happens If the HVAC System is Oversized?

An oversized HVAC system will use more energy, but won’t provide the most reliable or even cooling. Excess capacity will cause the unit to short-cycle and turn off before it fully warms or cools the space, resulting in uncomfortable temperatures and excess humidity.

How Long Does a Commercial HVAC System Last?

The average system lasts 12 to 15 years when you choose the right HVAC system for a large space and invest in regular maintenance.

What Are the Most Common Air Conditioning Systems Used in Large Buildings?

Central air conditioning is the most common system for large buildings. Very large industrial buildings typically use chillers, which distribute cooled water or liquids via a series of coils throughout the building.

Why Your AC Isn’t Cooling Your Business Properly

When your air conditioner fails to cool your business space during the hot and humid months, it can be incredibly frustrating – not to mention the impact it can have on overall comfort and productivity.

Here are seven common reasons why your AC might not be cooling your business like it should.

1. Frozen Evaporator Coil

A frozen evaporator coil is a frequent issue that directly affects the performance of a commercial property’s AC unit. The coil is designed to draw heat and moisture from indoor air when working correctly, but when it freezes, it means there may be a problem such as:

  • Dirty air filters
  • Malfunctioning fans
  • Leaking refrigerant

Regular maintenance checks can prevent these issues from becoming worse and ensure that the HVAC system runs smoothly.

2. Clogged Air Filters

Air filters can quickly become clogged due to the high activity in a commercial building.

A dirty air filter restricts airflow, forcing your AC unit to work harder and less efficiently. Make sure that air filters are checked and replaced regularly to maintain top performance.

3. Refrigerant Leak

An AC with low refrigerant may run – but it won’t properly cool circulated air.

Refrigerant is necessary to absorb heat from indoor air; when levels are low, there is no effective heat transfer. Refrigerant leaks require professional help to find and fix the source of the leak.

4. Dirty Condenser Coils

Condenser coils release the heat absorbed from your indoor space to the outside air. Over time, these coils can accumulate dirt and debris, particularly in commercial environments where outdoor air quality might be compromised. This build up prevents the release of heat, causing the system to circulate warm air back into your business.

Regular cleaning and maintenance of condenser coils are crucial.

5. Improperly Sized Air Conditioner

The size of your commercial AC unit matters.

Sometimes the floor plans change in a space. Sometimes heat loads are more than what the original design planned for cooling. An undersized unit will struggle to cool your space, while an oversized unit will be more prone to short-cycling, which means turning on and off repeatedly — causing poor cooling, high humidity, and higher energy bills. Make sure your HVAC system is properly sized for your business’s square footage, heat loads*, and cooling needs by consulting with an HVAC professional.

*Heat load is the heat-making objects in a space, i.e. number of people, equipment like computers, lights, copiers, machines, new windows allowing sunlight, etc.

6. Thermostat Issues

A malfunctioning/incorrectly set thermostat CAN affect your air conditioner’s performance. Make sure your thermostat is set to “COOL” and is functioning correctly.

FAN set to “Auto” means the blower runs only while cooling or heating. When the thermostat setpoint is satisfied, the blower or fan shuts off.

FAN set to “On” runs the fan continuously to keep circulating air within the space. Air moving across your skin is a cooling effect. Personal preference for comfort but know what the settings mean.

Issues like incorrect temperature calibration or installation site can result in poor cooling performance. A thermostat installed on a wall where sunlight shines through a window onto a wall or has a heat load (ex. copier machine) nearby will influence the sensitivity of temperature in the space.

Regular maintenance should include checking your thermostat’s settings, calibration, and wiring.

7. Leaky Ductwork

Damaged or leaky ductwork can result in cool air escaping before it reaches your workspace. If your HVAC ductwork is compromised, your air conditioner will run, but the cool air you’re paying for will be lost.

Call On Us for Commercial HVAC Services

At Interstate AC, we understand the unique needs of commercial properties. With over 20 years of experience serving Middle Tennessee, we provide reliable HVAC solutions tailored to your needs.

Call (615) 802-COOL (2665) to schedule a service or consultation with our expert team, and keep your business cool and comfortable throughout the summer months.

FAQs

How Often Should Commercial AC Filters Be Changed?

Filters in a commercial setting should be checked monthly and replaced as needed, typically every 1-3 months.

How Does High Humidity Affect Air Conditioning?

High humidity levels can make your business feel warmer than it is, even if your AC is working properly. The cooling process by design removes the moisture from the air. This moisture runs off the cooling coil and into drain lines that travel to the outdoors or deposits into the building drains. During high humidity months, those drain lines should be cleared or water leaks occur, or backed up water will force the equipment to shut off. Outside air should be reduced or minimized during these months as it introduces high humidity to the space. Equipment with economizers installed will have outdoor sensors which detect outside air temps and humidity, and will automatically close down or reduce intake.

Can We Repair A Refrigerant Leak Ourselves?

No, refrigerant leaks should always be handled by professionals due to the complexities and regulations involved.

Common AC Problem: Inadequate Cooling

During the summer, your air conditioner (AC) works harder and longer. That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

Inadequate Cooling

If your system is working fine (no leaks or noises, etc.), but it is not able to maintain the desired temperature you set on the thermostat, especially during the hottest part of the day, it could be that your unit is under-sized for your house. Perhaps you added space on to the house since it was built or removed trees near the house that were providing shade. When excessive demand is being made on the unit and it can’t keep up, you may need a larger unit. To delay having to get another system, you can add extra insulation – especially in the attic – and get double or triple paned windows with low E glass, to help improve your system’s performance. Getting regular tune-ups in spring and fall also helps to maintain your system’s efficiency so it will operate at peak performance. Other reasons for inadequate cooling include:

  • A dirty condenser or evaporator coil
  • A blocked condenser
  • Clogged drain lines
  • A lack of system refrigerant

Avoid AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.

Common AC Problem: AC Doesn’t Cycle On

During the summer, your air conditioner (AC) works harder and longer.  That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

AC Doesn’t Cycle On

If your AC does not cycle on, check to make sure it has power, that the circuit breaker has not been tripped, and that the thermostat is on and set to cool mode. If these check out, then here are some possible causes:

  1. System has frozen up: You might see ice on the inside or outside unit. This is typically a sign that there is a refrigerant leak (described above), but it could also be a sign that the ductwork is blocked or a dirty air filter. Turn the system off, turn the thermostat to fan, and wait for the ice to defrost, which may take several hours. Meanwhile, call an AC professional.
  2. Condensation (drip) pan is full: When condensate drips from the evaporator into the drip pan, the excess water should be carried away via pipes to the outside. If these pipes – the condensate lines – get clogged, a water float switch will automatically turn the AC unit off. If your unit is not equipped with a float switch, you will instead see water leaking from the around the drip pan. Dry out the drip pan and clean the condensate line. Refer to our post Clean Condensate Lines to Prevent Mold).

Avoid AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.

Common AC Problem: AC Blows Hot Air

During the summer, your air conditioner (AC) works harder and longer.  That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

AC is Blowing Hot Air

If your AC is not cooling or is blowing hot air, here are some possible causes and solutions:

  1. Thermostat turned to heat mode: Switch it back to “cool” and you’re good to go.
  1. Dirty evaporator coil caused by a dirty air filter:  Change air filters.  You may also need to have the evaporator coil (inside the indoor part of the AC unit) professionally cleaned.
  1. Condenser coil obstructions: Check the outside AC unit for anything blocking the condenser’s air flow, and clean any debris (such as grass clippings, overgrown bushes, etc.) around the unit.
  1. Low on refrigerant/Freon:  This is usually caused by a refrigerant leak somewhere in the system and looks like ice forming on either the inside or outside unit or both.  For this, you’ll need to contact an AC professional.  See our post Adding Freon to your AC is NOT a DIY Project.

Avoid AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.

Common AC Problem: AC Runs Continuously

During the summer, your air conditioner (AC) works harder and longer.  That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

AC Runs Continuously

Perhaps the AC is cooling but you notice it’s working harder and longer.  You might also notice a sharp increase in your energy bills compared to last year at the same time.  This may be due to a sensor problem, which is causing improper monitoring of the temperature of the evaporator coil.  Typical sensor problems include: the sensor isn’t positioned in the right place, the connections to and from the sensor have failed (due to an electrical short, for example), or the sensor itself has died.  A professional AC technician will be needed to investigate and remedy these situations.

Avoid AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.

Common AC Problem: Unit Shuts Off Repeatedly

During the summer, your air conditioner (AC) works harder and longer.  That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

Unit Shuts Off Repeatedly

If the unit is turning on and off repeatedly, or has difficulty switching on, or you hear a choking and stuttering sound while turning it on, there is short cycling problem.  This can severely damage the compressor, stress the other components, and will consume excess electricity.  Some possible causes are an electrical short somewhere in the system, poor wiring (this is serious and could cause a fire), a damaged or failed part in the system, dirty air filters, or blocked ducts preventing the flow of air.  If you continue to have a short cycling problem after checking your air filter and vents, turn the system off and contact an AC professional.  In some cases – especially if the problem has persisted a while – you may require a new AC unit entirely..

Avoid AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.

Common AC Problem: Noises

During the summer, your air conditioner (AC) works harder and longer.  That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

Noises

While your AC is running, you should hear the hum of the blower, a click when your air conditioner turns on, and the whir of the outside condenser fan.  Other noises – such as rattling, screeching, thumping, clanging, or banging – mean your system is having problems.  Typical causes of noise from the AC unit include: a belt wearing out, loose hardware, a failing motor, refrigerant issues, or blower issues.  But try these things first: make sure the filter is clean, that the air vents in all rooms are unblocked, and that there are no obstructions around or in the outside unit.  If you still hear strange noises, contact a professional AC service technician before the situation worsens and leads to big repair bills and prolonged downtime.

Avoid AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.

Common AC Problem: External Fan Not Working

During the summer, your air conditioner (AC) works harder and longer.  That high demand may cause a problem to rear its ugly head.  In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.

External Fan (Compressor) Not Working

Check all around and inside the outdoor unit.  Verify that the fan blades are unimpeded.  It could be that the outdoor unit sustained damage due to falling debris from storms.  Be sure to keep the area around the outdoor unit clear of debris and check it often throughout the summer and fall.  If there are no obstructions and the fan blades are not turning, it could be caused by a lack of power to the system.  Cycle the power by turning the circuit breaker off and back on again, then set the thermostat lower than the current inside temperature and wait 2-5 minutes.  If you do not hear the compressor kick in and the fan blades start to turn, you probably have a faulty motor or compressor, and will need to contact a service professional.

Avoid Summer AC Problems

Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it.  Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat.  If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.