index.php

The purpose of HVAC systems goes beyond that of just simply heating and cooling a space. The more valuable design to this system is to improve the air quality, which in turn, improves comfort to any building interior. An HVAC unit is an important mechanical feature, which, like any system, can result in some technical problems if not monitored.

For an HVAC engineer, evaluating, managing and troubleshooting the issues with HVAC is all a part of their scope. The system itself can be complicated and it is very beneficial and important to have a professional HVAC engineer regulate any large issues with your system.

However, to prevent these large issues, it’s even more responsible to have regular troubleshooting done, which in turn, can supply a lot of benefits in the long-run. 

Energy Cost Savings

Preventative maintenance holds true to most mechanical systems – meaning, that with any HVAC system, the regular maintenance you hold on your system has substantial benefits to the efficiency in how it runs. This efficiency in the energy consumption of the unit, means great energy savings, and cost savings, long-term. 

Mechanical  room with HVAC system

Avoid Costly Repairs 

HVAC engineering system

As mentioned earlier, an HVAC mechanical engineer can help regulate any large issues with the system. However, troubleshooting your system regularly can mean avoiding the expense of bringing someone in to resolve an even bigger problem. This regular maintenance can improve the lifespan of your system and overall reduce the cost of a mechanical engineer having to manage the replacements of certain components, which could be costly. 

After all, you wouldn’t go over 3,000 miles without an oil change for your car – the same analogy holds true for regular maintenance and troubleshooting on your HVAC unit. Take care of your systems, and they will continue to take care of you. 

Comfortable and Appealing Commercial Space

Just as much as you depend on your HVAC system keeping you comfortable all year round – so do your tenants or clients. Regular maintenance and troubleshooting will help your HVAC unit produce air flow that will distribute warm or cool air evenly throughout your space. 

As a property owner, it’s essential to provide a comfortable and appealing place for short and long term rentals. The same goes as a company owner, and ensuring your space is comfortable and appealing to all current and future clients. Temperature regulation is important, however, troubleshooting your HVAC system can also improve quality of life in regard to silencing noise or reducing smell that builds up in the equipment over time. 

Roof HVAC engineering unit

Conclusion

It’s not just about maintaining; it’s about getting full value and redeeming the benefits of a fully functional HVAC unit that is reliable, and consistent. At Falcon Engineering, we understand the execution of HVAC designs that are reliable, consistent and most importantly, energy efficient. 

We provide niche engineering services in the sustainable energy space; as a leader in geoexchange engineering services and energy modelling, our responsibility is to provide mechanical solutions tailored to the needs of our clients. Our commitment is to long term solutions, and in-house resourcefulness for our clients. 

If you are interested in our mechanical service offerings, you can find more information about how we help clients find solutions here.

Want to learn more about mechanical engineering? Check out some of our other blogs!

Written By Don Poole, P.Eng.

Falcon Engineering frequently performs surveys on existing buildings prior to an HVAC upgrade. Sometimes the equipment is ageing, or sometimes occupant comfort complaints trigger the upgrade. Here are the most common and effective means to improve comfort if air systems are being used to heat and cool spaces (if the terminal equipment is correctly sized). 

1. One Unit for One Zone

Similar loaded rooms can be combined into one zone.

My mentor, Doug Joorisity, and I sorted this one out years ago when the smallest rooftop unit that was available was 5 tons. We would often design two classrooms to be served by a single rooftop unit. The classroom with the thermostat was always comfortable, while the classroom without suffered significant temperature swings. Applying Variable Volume Variable Temperature (VVT) systems to this situation did not end satisfactorily. Once the 2½ ton rooftop unit became available, you could implement an appropriate solution.

A group of offices, such as a group of councilors rooms, can be considered a single zone if they: 

  • Share an outside wall
  • Have the same window size 
  • Have the same floor space

The room temperatures can be very similar in each room. The only problem might be that the occupant may want different temperatures.    

2. Ducted Low-Level Return

Reduces stratification and short-circuiting, improves ventilation effectiveness and saves energy.

When I was in high school, I noticed in winter that the woodshop mezzanine where projects were stored was always significantly warmer than the main floor. I didn’t think much of that until I became an HVAC engineer and noticed that the return air in these woodshops was at ceiling level. In an upgrade to one of these woodshops, with School District 23 in Kelowna, we installed a ducted return air grille at the floor level. Matt Garbelya at the District helped us figure a way to get a filter into the low-level return to keep fine sawdust out of the return duct. By using infrared temperature measuring devices, we could see the hot air, which would have been stratified to the ceiling, drawing down to the floor. 

After that, we employed a low-level return system at a large secondary school in Prince George. The existing system was multi-zoned, using the ceiling space as a return plenum and the return air grilles were merely egg crates mounted in the T-Bar ceiling. The upgrade replaced the old multi-zone systems with new ones, with low-level ducted returns employed in each classroom. The results? A school considered chronically cold in the winter became comfortable. The management noticed significant gas bill savings, and students were no longer wearing their winter jackets all day.  

School gymnasium with students playing sports
One low-level ducted return can eliminate stratification in this whole gym.

3. Positive Building Pressures

Minimizes drafts.

Rob Bruce, a sage and experienced commissioning agent, taught me that slightly positive pressure in a school significantly improves comfort. He spent many years in northern Alberta and knew how much difference it makes. 

The point of pressurizing a building during the occupied mode is to eliminate drafts through the building envelope. We deployed methodology on a significant HVAC upgrade at a school in the Okanagan Valley. Prior to the upgrade, the receptionist in the central office near the main entryway was always cold. They even had an electric heater under desks to warm their feet. When interviewed after the building was positively pressurized, they reported that they didn’t need the heater all winter, and they were considering removing the heater completely!   

4. Dedicated Relief Exhaust

Enables full economizing. 

I completed an HVAC update at a school in Vernon. It was an older school, and I assumed that the building was leaky enough that a relief system wouldn’t suffice. That was at a time when we started to use demand control ventilation, so we measured CO2 levels. We noticed that CO2 levels in one room, in particular, would sometimes spike way beyond the limit. We experimented with the teacher – one full-class day with the door to the room closed and one day with the door open. The trend logs showed that, with the door open to form the relief path, the CO2 could be maintained at acceptable levels. We introduced a dedicated relief exhaust system and solved the CO2 problem. In addition, we achieved full free cooling (also known as economizing). Without the relief exhaust, such function was severely hindered. 


The moral of that story is “You can only shove air into a pop bottle for so long”! 

HVAC Vent on a roof
Dedicated relief exhaust with a gravity backdraft damper, used to serve a large portion of the school.

5. Tempered Outside Air

Natural ventilation isn’t effective when it is -18°C (0°F) outside

A new college building in the Interior was designed to employ natural ventilation for the outside air source. We deemed the stack effect insufficient, so we introduced large fans to create a negative pressure in the atrium. Some of the outside air was tempered, but the bulk of outside air entering the building leaked through building envelope cracks. The design resulted in awful cold drafts. 

We introduced a make-up air system to reduce the negative pressure, and it helped, but nearly every single office in the whole building had a plug-in electric heater. Whatever energy the original designer hoped to save with the natural ventilation system was more than lost with the electric heaters. It was unfortunate that so many people suffered needlessly. 

tempered outside air outlets
Down blast air outlet was so bad that it was necessary to install a sheet metal deflector.

6. Air Outlet Velocity in the Occupied Zone is Less Than 0.25m/s (50 feet per minute)

A school hired us to investigate a problem in which classroom occupants complained of drafts. Linear diffusers were initially installed at the perimeter (presumably to wash the wall), but they were installed about 2 meters off the wall. The air outlets were too noisy with the outlets aimed horizontally, so the air outlets were left pointing downward. The cooling mode produced intolerable drafts. We replaced the linear diffusers with standard cone-style diffusers, solving this draft problem.

Conclusion

Configuration of the supply and return air systems in a classroom will significantly impact occupant comfort. This is especially true for areas experiencing extreme outdoor temperatures for both heating and cooling. We have seen significant comfort improvements in deploying the above strategies, so it’s well worth the time and effort to keep these tactics in mind during the initial HVAC design. In some cases, we see significant energy savings as well.

Let us know if you have any questions by using our contact page!

Want to learn more about mechanical engineering? Check out some of our other blogs!