Retail and shopping centre HVAC

Retail buildings range from a single store in a strip plaza to enclosed regional shopping centres with hundreds of tenants, a food court and a cinema. The HVAC challenges differ with scale, but some themes are constant: high and variable occupancy, large door openings, heavy lighting in older stores, long operating hours and a split of responsibility between landlord and tenant that shapes almost every design decision.

The landlord and tenant split

In most Canadian retail properties, responsibility for HVAC is divided by the lease. Typical arrangements include:

• Strip plazas and power centres: each tenant has one or more dedicated rooftop units, owned or maintained by the tenant or by the landlord with costs recovered through common area maintenance charges.
• Enclosed malls: the landlord operates central systems for common areas such as concourses, washrooms and food courts. Tenants may receive chilled water, condenser water or heating hot water from the base building, or they may install their own rooftop units.
• Anchor stores: large department stores and grocers usually operate independently with their own systems.

The lease and the landlord's tenant design criteria define what the tenant receives: tonnage allowance, connection points, exhaust provisions and controls integration requirements. Weak tenant criteria are a frequent source of long-term problems, such as tenants adding undersized units or kitchen exhaust without make-up air.

Loads in retail spaces

Retail loads vary widely by tenant type.

Occupant density varies sharply by time of day and season. ASHRAE 62.1 lists a default of 15 people per 100 m2 for sales floors and 40 per 100 m2 for mall common areas, but peak holiday shopping can exceed those, while weekday mornings see a fraction. This makes retail a good fit for demand-controlled ventilation.

Grocery stores

Grocery stores need particular attention. Open refrigerated cases cool and dehumidify the space around them, which can make aisles uncomfortably cold in winter while other areas need cooling. Space humidity control matters because high humidity increases frost on refrigerated cases and raises refrigeration energy. Many grocery designs use dedicated dehumidifying units and, increasingly, heat recovered from the refrigeration system for space and water heating.

Rooftop units

Packaged rooftop units are the workhorse of Canadian retail. They are relatively inexpensive, easy to replace, and each tenant can be metered and controlled independently. For guidance on selecting them, see rooftop unit selection for commercial buildings.

Key considerations for retail rooftop units:

• Economizers: properly working economizers provide substantial free cooling in Canada's climate, but economizer failures are among the most common faults found on rooftop units.
• Heating capacity: gas-fired heating sections must handle both envelope losses and the outdoor air load at design temperatures, which reach below -30 C (-22 F) in Edmonton and Winnipeg.
• Heat pump units: cold-climate packaged heat pumps are increasingly used for electrification, often with backup gas or electric heat.
• Replacement planning: a large plaza may have dozens of units of different ages. A replacement plan avoids emergency replacements during peak season.

Entrances and building pressure

Retail entrances open constantly, letting in cold air in winter and hot humid air in summer. Strategies to manage this include:

1. Vestibules: required by the energy code in many cases for larger entrances, and very effective when the two sets of doors are spaced so they are not open at the same time.
2. Entrance heaters and air curtains: cabinet unit heaters or air curtains at vestibules reduce drafts at checkouts near the door.
3. Positive building pressure: supplying slightly more outdoor air than is exhausted keeps outdoor air from rushing in. Excess exhaust from kitchens or washrooms without matching make-up air is a common cause of negative pressure and cold entrances.
4. Revolving doors: effective in high-traffic enclosed malls and office-retail complexes.

Our guide to building pressurization and infiltration control explains how to measure and correct pressure problems.

Food courts and restaurants

Food service tenants bring commercial kitchen exhaust hoods, grease ducts and make-up air, all governed by NFPA 96 as referenced by the building and fire codes. In malls, the landlord typically provides a grease exhaust riser or requires each tenant to route its own duct to the roof.

The make-up air question is critical. If kitchen exhaust is replaced by air drawn from the mall concourse, the common area systems must be sized to supply it, and cooking odours may spread. Dedicated make-up air units, often direct-fired or indirect-fired gas, are usually required. See commercial kitchen ventilation and NFPA 96 for details.

Enclosed mall common areas

Mall concourses often have large skylights, high ceilings and heavy pedestrian traffic. Typical systems include central air handlers serving the concourse with tenants drawing transfer air from it, or rooftop units distributed along the mall.

Common issues include stratification under skylights, overheating on sunny spring days, and draft complaints near entrances. Many older malls were designed for very high lighting loads and have significantly oversized cooling capacity after LED retrofits, which can lead to short cycling and poor humidity control.

Energy opportunities

Retail energy use is dominated by long operating hours, so controls matter most:

• Align HVAC schedules with actual store hours, including restocking shifts.
• Verify economizer operation on every rooftop unit.
• Use demand-controlled ventilation in large sales floors and mall concourses.
• Recover refrigeration heat in grocery stores.
• Retro-commission central systems after lighting retrofits to rebalance airflow and reset cooling capacity.

An energy audit across a retail portfolio often finds the same handful of control problems repeated at many sites.

Frequently asked questions

Who pays for HVAC replacement in a retail lease?

It depends on the lease. In many net leases the tenant pays for repairs and the landlord funds capital replacement, but the opposite is also common. The lease language governs.

Why are the checkout lanes always cold?

Checkouts are usually near entrances, so they get infiltration every time the doors open. Negative building pressure from unbalanced exhaust makes it worse. Vestibule heating, air curtains and correcting building pressure are the usual fixes.

Key takeaways

• Lease terms and tenant design criteria shape retail HVAC more than in almost any other building type.
• Rooftop units dominate, and economizer and heating section reliability are the main performance issues.
• Entrance infiltration and negative building pressure cause many retail comfort complaints.
• Food service tenants need properly designed exhaust and dedicated make-up air under NFPA 96.
• Grocery stores need humidity control and offer good opportunities for refrigeration heat recovery.
• Schedules, economizers and demand-controlled ventilation offer the largest energy savings.