Small Box Retail
Small box retail stores - less than 10,000 square feet - can range from discount and variety stores located in old buildings to chain drug stores located in brand new buildings.
They range from small owner operations which are usually undercapitalized, to franchises prescribing certain of their operational limits, to chains with firm headquarters control over energy system designs, specifications, and operations.
The selection and design of HVAC systems for small box retail facilities are normally determined by economics. First cost is usually the determining factor for small stores; for large retail facilities, operating and maintenance costs are also considered. Generally, decisions about mechanical systems for retail facilities are based on simple payback or a cash flow analysis rather than on a full life-cycle analysis.
Small stores often have large frontal glass areas which could result in high peak solar effects (except for north facing stores). High heat loss can also occur on cold, cloudy days. This portion of the store should be designed to offset these higher cooling and heating requirements. Entrance heaters may also be used in cold climates.
Department stores vary in size, type, and location. Each store should have an air- conditioning system design that meets its particular needs. Sufficient outdoor air must be supplied to minimize or eliminate odor problems. Basic features of a quality system include (1) an automatic control system to handle changing loads, (2) main sales areas zoned for air distribution to maintain comfort conditions with varying loads, and (3) use of an economizer system for cooling during intermediate seasons and peak sales periods.
Design the system to maintain relative humidity at 50% or below with a corresponding dry-bulb temperature of 78°F. This humidity limit eliminates musty odors and retards perspiration, particularly in fitting rooms. It is also desirable to adjust indoor temperatures for variations in outdoor temperatures, to avoid temperature shocks as customers enter and leave the store. Winter humidification is seldom used in store air conditioning.
Single-zone unitary rooftop equipment with prefabricated and matching curbs simplifies installation common in small box store air conditioning. The use of multiple units to condition larger stores involve less ductwork and can maintain comfort in the event of partial equipment failure. These HVAC units may be either heat pumps or gas heating/electric cooling packages. This equipment is air-cooled and has a low first cost and ease of operation, which readily adapts them to small-store applications.
Water-cooled cooling equipment is available for small-store air conditioning, but many communities have restrictions on the once-through use of city water and require the installation of a cooling tower or other water-conserving equipment. Water-cooled equipment generally operates more efficiently and economically, but higher first cost with a tower and higher maintenance limits its application.
Retail facilities often have a high sensible heat gain relative to the total heat gain and equipment should provide the necessary sensible heat removal. The external static pressures available in small-store air-conditioning units are limited, and duct systems should be designed to keep duct resistances low. Duct velocities should not exceed 1200 fpm and pressure drops should not exceed 0.10 in. of water per 100 ft. Average air quantities range from 350 to 450 cfm per ton of cooling in accordance with the calculated internal sensible heat load.
Some of these stores may contain restaurants and lunch counters. These special areas may operate during all store hours. They may be met by the portion of the air conditioning system serving or by a separate air-conditioning system. The restaurant is often used only during the noon hours. For control of odors, a separate air-handling system should be considered.
Energy Saving Recommendations
- Older inefficiency cooling and heating systems should be investigated for upgrading or replacement, particularly if CFC refrigerants are used.
- Where demand and/or on-peak energy costs are high, investigate thermal storage.
- Add Economizer cycles if they are not installed or in use.
- Upgrade antiquated or inappropriate control systems.
Water heating is not a major energy user with uses typically for hand washing and cleaning purposes. Most water heating is done separately from the building heating system using direct resistance or gas heaters, and in some cases, point-of-use heaters. Central distribution systems with storage and constant recirculation are seldom used in these stores.
Energy Saving Recommendations
If existing systems are inefficient or inadequate, replace with modern efficient equipment. If a source of waste heat (i.e. tower water) is available, consider a water-to-water heat pump heater. Instantaneous water heaters should be considered for restrooms.
Some stores may contain restaurants and lunch counters. Their cooking needs should be handled as appropriate.
In retail situations, the obvious function of lighting is to enable the shopper to examine the products offered and read any packaging information. More importantly, the lighting helps the shopper to identify with the level of merchandise and service. So lighting designed to communicate these values between retailer and shopper is an indispensable part of gaining a competitive edge.
Each retail establishment has distinctive features that hopefully make it attractive to a specific customer and reinforce its sales strategy. These include the range of products, style of service and the interior design, including the lighting design.
Lighting systems in small box retail stores usually includes a mix of incandescent and fluorescent fixtures. Metal Halide can be found in many of the newer stores.
Energy Saving Recommendations
The primary purpose of the retail lighting is the effect or esthetics. However, metal halides and compact fluorescents can frequently provide the same effect as incandescent and T-8 fluorescents are great replacements for T-12 Fluorescents.