HVAC Design

Balancing Tenant Comfort and HVAC Design

For many property managers, it can be challenging to balance the indoor environment of a building with the comfort of its occupants
Monday, October 31, 2016
By Douglas Lee

“Hello. I have several tenants in my building, complaining that their space is too warm or stuffy. I also have a few tenants telling me their suite entrance doors do not close properly. Can you help us?”

Sound familiar? It’s the kind of call property managers should not have to make to an engineering firm because complaints such as these often result from poor indoor air quality.

If an HVAC system is well-designed, with proper air quality and air flow, tenants will be satisfied and property managers will field fewer complaints. But if a system is poorly designed, the inadequate air flow that results will leave tenants feeling dissatisfied and unproductive.

Or worse. Some tenants have taken matters into their own hands, adjusting the thermostats to full heating or cooling, adjusting the dampers to the supply diffusers and blocking the outlet grilles on the perimeter induction units at the windows. Before long, the HVAC system is malfunctioning, disrupting the comfort level and air balance within a tenant space, while also affecting the HVAC system in the entire building and, therefore, the overall indoor air quality.

For many property managers, it can be challenging to balance the indoor environment of a building with the comfort of its occupants. Working with an engineer on a competent HVAC design can help accommodate both of these needs. Here are some simple ways to accomplish a good design that will provide high indoor air quality and comfort levels.

Engineer It

Asking an engineer to design your renovations is a key first step towards ensuring the HVAC system will meet the needs of tenant space and will comply with all local bylaws, such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the Ontario Building Code (OBC).

An engineer will also guarantee that tenants’ requirements are incorporated into the design, such as noise levels, temperature settings, humidity levels, power requirements, lighting levels and lighting control. This is a simple but very important process.

In some cases, after finding out what the requirements are, a property manager may have to inform tenants that certain requirements may not be possible, given the limitations of the building’s existing HVAC and electrical systems

The age of an HVAC system or the excessive needs of a client’s space—a call centre or after-hours operation, for instance—may cause these limitations, resulting in the need for revisions to main building systems.

Taking a Look See

Another key component of a good design is a good site survey. Prior to any design, a survey of the existing HVAC system must be completed. A drawing-based design is not recommended because it will only lead to inaccurate design drawings, resulting in additional costs.

The HVAC system within the tenant space must be traced. This also extends to the water supply, drain service (floor below), sanitary vent line, power distribution, main service feeder and panel/disconnect, communication devices, lighting fixtures and life safety devices.

Working with the Building Operators

Collaboration between the engineer and building operator is an important step in delivering a good design. Aside from accessing the tenant space, engineers will require assistance from the building operator to access electrical and mechanical rooms. Building operators can also provide critical insight into the operation of their systems, such as operating hours, air handling system performance during extreme outdoor conditions and problem areas in the HVAC distribution system.

HVAC Design

Base Building Drawings

Base building as-built drawings act as a roadmap, giving engineers an overall view of how mechanical and electrical systems are installed.

The drawings will also help the engineer determine where to look for future capped connections for the drain, water supply and venting, as these services are located either at the core or at columns called “wet stacks,” which are within the tenant space.

Don’t Tax Me

One building’s HVAC system is not like the other. The HVAC system operating in a 1950’s building will not have the same operating characteristics or capacity as a building built in the 2000’s. Design parameters, such as outdoor air supply and total air flow, used to be much lower compared to today’s design standards. Therefore, a design must be adaptable to accommodate the tenant’s requirements, along with the limitations of the HVAC system.

You should never design for more air supply than what is typically allowed for a tenant’s space as it relates to the overall floor area.

Depending on the circumstances, supplemental cooling and/or outdoor air supply may be required for service, call centres, training rooms, IT rooms or meeting rooms. These systems will be independent of the building’s HVAC system.

Show Me the Way Home

Designing a proper return air path back to the base building return air duct is very critical to the operation of the overall air supply system; however, this component is often overlooked. Having up-to-date base building drawings will assist in determining the return air pattern.

Tenant demising walls are usually constructed as full height walls that run from the floor slab to the ceiling deck, with each tenant space sealed onto another. Since the main building return air duct is typically located at one end of the floor, transfer air openings in the demising walls must be installed to allow the return air to flow from one tenant space to another, eventually returning back to the main return air duct.

To minimize noise transmissions between tenancies, these openings are installed with internally insulated duct sections open at each end. Without proper air transfer, buildings can experience stuffy conditions due to stagnant air flow and doors that do not close properly, creating security issues, as well as stack effects through the elevator shaft or stairwell.

Whether a building is old or new, creating good engineering designs requires simple common sense thinking.

Get a Permit

Most renovations will require a city permit. This step is required by law and should never be overlooked. Having a permit will ensure that the engineering drawings have been completed to code.

A permit will also confirm that construction has been completed as outlined in the permit drawings. Engineers are required to perform periodic reviews of the construction, as part of the permit. This is another layer of protection that will ensure that the contractor installs what has been designed.

Closeout

Finally, once construction has been completed, a last inspection will ensure that the installation has been completed according to the design drawings, all deficiencies outlined in the periodic inspections have been addressed and all systems are operating as designed.

In most cases, city inspectors will request to have the engineer sign-off letters prior to the city’s inspection and before they can grant occupancy.

 

Douglas Lee, principal at M & E Engineering, is an accomplished designer with more than 20 years of progressive and sound experience managing all technical aspects of design projects. Through his many years of service, he has carried out, performed, managed and supervised a diversity of mechanical and electrical design projects. Lee is currently the head of the tenant division, whereby he oversees and administers M & E’s mechanical and electrical team of professional engineers and designers for various renovation projects in the commercial, retail and industrial industry. 

To learn more about balancing HVAC design with tenant satisfaction, connect with professionals at M & E Engineering Ltd.

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