Exploring retail, restaurant, and mixed-use facilities: HVAC and sustainable buildings/energy efficiency

Respondents

• Dale Adney, PE, Project Engineer, RTM Engineering Consultants, Chicago
• Juan L. Castro, LEED AP, Principal/Mechanical Engineering/Retail Studio Manager, Thorson • Baker + Associates, Richfield, Ohio
• Eric Graettinger, PE, LEED AP BD+C, Vice President, Peter Basso Associates Inc., Troy, Mich.
• Robert A. Kamm, PE, LEED AP, BD&C, CxA, CEO, KAMM Consulting Inc., Deerfield Beach, Fla.
• Bradley D. Williams, PE, Vice President, MEP, Bala Consulting Engineers, New York City

CSE: What unique heating and cooling systems have you specified in such projects? Describe a difficult climate in which you’ve designed an HVAC system.

Williams: Implementing differing HVAC technologies in mixed-use projects can help yield a greater overall system efficiency for the building. Implementing demand ventilation for retail occupancies, demand-control kitchen ventilation for restaurant areas, and VRF systems with individual control and heat-recovery capabilities in residential areas have proven to increase the energy savings for buildings while maintaining code-required ventilation rates.

CSE: What types of air economizers or other strategies are owners and facility managers requesting in restaurant, retail, and mixed-use facilities?

Adney: Through the use of DOAS and VRF systems, we are able to avoid the need for economizers and gain exceptions to a number of prescriptive requirements to which other HVAC systems are subject.

CSE: What types of air balancing do you typically include in your designs? Describe the project.

Graettinger: Typical specifications call for air and hydronic water test and balancing including supply air (terminal devices and units), return air, toilet exhaust, kitchen hood exhaust, etc.

CSE: When working in restaurants (or mixed-use facilities), describe the HVAC ventilation system, which might include vent hoods, fire suppression systems, or other specialized ventilation systems.

Adney: King of HVAC in restaurants is the kitchen hood and associated make-up air. They are the stars of the show and drive a lot of how the space functions. Heating and cooling can be provided by a wide variety of equipment. Air handlers that mix ventilation with the heating/cooling is usually most economical, but when so much air is coming and going through the kitchen, having to provide relief with an economizer via separate fans or power exhaust can add one more challenge to a tenuous pressure balance. Many food service providers see all the outside air required to provide fresh air to their full dining rooms and hope to use this as make-up air for their high-exhaust kitchens. At first glance, this appears to be a viable strategy, but it often runs into complications. Hoods must be provided with make-up air very close to the hood to properly capture grease and smoke. Additionally, transferring air across the only opening between the kitchen and the dining space (where the food sits) may have negative "cooling" effects on the meals.

Williams: Demand-control kitchen ventilation is becoming more prevalent in the restaurant market, especially in the high-end food court environment. This system allows for the reduction in exhaust air under reduced hood-load conditions. Hood technology has improved to the extent that many hood variables can be monitored (hood-capture profiles, temperature, infrared sensing technology, interconnection of systems, and speed of response). This reduced airflow translates directly into make-up air reductions, thus it is a cost savings to the owner/operator.

CSE: What types of sustainable features or concerns might you encounter on such facilities that you wouldn’t on other projects?

Castro: I’ll come at this from a slightly different angle—I actually find it more challenging to convince smaller tenants about the benefits of sustainable design. Sometimes "because it’s good for the environment" is not a good enough answer. Some tenants are only concerned with first costs, so part of my job is to educate them, comparing sustainable features with other energy-saving design strategies that will pay off in the future including:

• Roof: Provide better insulation than the code minimum (R-30); provide superior radiant insulation.
• Walls: Provide better insulation than the code minimum (R-20).
• Slab: Provide better insulation (R-10 for 24 in., full perimeter).
• Doors: Provide better insulation (U-0.50).
• Vertical glazing: Keep the area of glazing to a minimum; use exterior sun control (overhangs); use better insulation (U-0.38); use a better solar heat gain coefficient (0.36).
• Interior lighting: Use a lighting density of no more than 1.3 W/sq ft; use a linear and compact fluorescent with a high-performance electronic ballast (or LED lighting where appropriate); provide dimming controls or multilevel switching; provide occupancy controls; provide daylighting controls at areas adjacent to glazing.
• HVAC: Use high-efficiency equipment; take advantage of economizers; use a motorized damper for outside-air control; use carbon dioxide sensors (for demand control); insulate ductwork using R-6 at minimum.
• Plumbing: Use high-efficiency plumbing fixtures for less water usage; insulate all cold-water and hot-water piping. These are all small things that can add big savings in the future.

CSE: High-performance design strategies have been shown to have an impact on the performance of the building and its occupants. What value-add items are you adding to restaurant, retail, and mixed-use facilities to make the buildings perform at a higher level?

Williams: The balance between exhaust air and outside air is always of paramount concern for these facilities. Whereas LEED allows for an increased ventilation credit, most owners are knowledgeable and desire the reduction of outside air to minimum code-required levels to save costs on installation and operation attributable to higher ventilation rates. Implementing strategies, such as electronic media filtering to the outside-air stream, can lead to enhanced employee performance as well as potential reduction in outdoor-air rates; although more field data is required to vet this over the long term.

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