ASHRAE HVAC APPLICATIONS IP CH 2-2015 Retail Facilities.pdf

1、2.1CHAPTER 2 RETAIL FACILITIESGeneral Criteria. 2.1Small Stores 2.1Discount, Big-Box, and Supercenter Stores. 2.2Supermarkets 2.3Department Stores 2.5Convenience Centers 2.6Regional Shopping Centers 2.7Multiple-Use Complexes 2.7HIS chapter covers design and application of air-conditioningTand heatin

2、g systems for various retail merchandising facilities.Load calculations, systems, and equipment are covered elsewhere inthe Handbook series.1. GENERAL CRITERIATo apply equipment properly, the construction of the space to beconditioned, its use and occupancy, the time of day in which greatestoccupanc

3、y occurs, physical building characteristics, and lightinglayout must be known. The following must also be considered: Electric power: size of serviceHeating: availability of steam, hot water, gas, oil, or electricityCooling: availability of chilled water, well water, city water, andwater conservatio

4、n equipmentInternal heat gainsEquipment locationsStructural considerationsRigging and delivery of equipmentObstructionsVentilationopening through roof or wall for outdoor air ductExposures and number of doorsOrientation of storeCode requirementsUtility rates and regulationsBuilding standardsSpecific

5、 design requirements, such as the increase in outdoor airrequired to make up for kitchen exhaust, must be considered. Venti-lation requirements of ASHRAE Standard 62.1 must be followed.Objectionable odors may necessitate special filtering, exhaust, andadditional outdoor air intake.Security requireme

6、nts must be considered and included in theoverall design and application. Minimum considerations requiresecure equipment rooms, secure air-handling systems, and outdoorair intakes located on the top of facilities. More extensive securitymeasures should be developed based on overall facility design,o

7、wner requirements, and local authorities.Load calculations should be made using the procedures outlinedin the ASHRAE HandbookFundamentals.Almost all localities have some form of energy code in effect thatestablishes strict requirements for insulation, equipment efficien-cies, system designs, etc., a

8、nd places strict limits on fenestration andlighting. The requirements of ASHRAE Standard 90.1 must be metas a minimum guideline for retail facilities. The Advanced EnergyDesign Guide for Small Retail Buildings (ASHRAE 2006) providesadditional energy savings suggestions.Retail facilities often have a

9、 high internal sensible heat gain rel-ative to the total heat gain. However, the quantity of outdoor airrequired by ventilation codes and standards may result in a highlatent heat removal demand at the equipment. The high latent heatremoval requirement may also occur at outdoor dry-bulb tempera-ture

10、s below design. Unitary HVAC equipment and HVAC systemsshould be designed and selected to provide the necessary sensibleand latent heat removal. The equipment, systems, and controlsshould be designed to provide the necessary temperature, ventila-tion, filtration, and humidity conditions.HVAC system

11、selection and design for retail facilities are nor-mally determined by economics. First cost is usually the determin-ing factor for small stores. For large retail facilities, owning,operating, and maintenance costs are also considered. Decisionsabout mechanical systems for retail facilities are typi

12、cally based ona cash flow analysis rather than on a full life-cycle analysis.2. SMALL STORESSmall stores are typically located in convenience centers and mayhave at least the store front exposed to outdoor weather, althoughsome are free standing. Large glass areas found at the front of manysmall sto

13、res may cause high peak solar heat gain unless they havenorthern exposures or large overhanging canopies. High heat lossmay be experienced on cold, cloudy days in the front of these stores.The HVAC system for this portion of the small store should bedesigned to offset the greater cooling and heating

14、 requirements.Entrance vestibules, entry heaters, and/or air curtains may be neededin some climates.Design ConsiderationsSystem Design. Single-zone unitary rooftop equipment is com-mon in store air conditioning. Using multiple units to condition thestore involves less ductwork and can maintain comfo

15、rt in the event ofpartial equipment failure. Prefabricated and matching curbs simplifyinstallation and ensure compatibility with roof materials.Air to air heat pumps, offered as packaged equipment, are readilyadaptable to small-store applications. Ground-source and otherclosed-loop heat pump systems

16、 have been provided for small storeswhere the requirements of several users may be combined. Winterdesign conditions, utility rates, maintenance costs, and operatingcosts should be compared to those of conventional heating HVACsystems before this type of system is chosen.Water-cooled unitary equipme

17、nt is available for small-store airconditioning. However, many communities restrict the use of citywater and groundwater for condensing purposes and may requireinstallation of a cooling tower. Water-cooled equipment generallyoperates efficiently and economically.Air Distribution. External static pre

18、ssures available in small-store air-conditioning units are limited, and air distribution should bedesigned to keep duct resistances low. Duct velocities should notexceed 1200 fpm, and pressure drop should not exceed 0.10 in. ofwater per 100 ft. Average air quantities, typically range from 350 to450

19、cfm per ton of cooling in accordance with the calculated internalsensible heat load.Attention should be paid to suspended obstacles (e.g., lights,soffits, ceiling recesses, and displays) that interfere with proper airdistribution.The preparation of this chapter is assigned to TC 9.8, Large Building

20、Air-Conditioning Applications.2.2 2015 ASHRAE HandbookHVAC ApplicationsThe duct system should contain enough dampers for air balanc-ing. Volume dampers should be installed in takeoffs from the mainsupply duct to balance air to the branch ducts. Dampers should beinstalled in the return and outdoor ai

21、r ducts for proper outdoor air/return air balance and for economizer operation. Control. Controls for small stores should be kept as simple aspossible while still providing the required functions. Unitary equip-ment is typically available with manufacturer-supplied controls foreasy installation and

22、operation.Automatic dampers should be placed in outdoor air inlets and inexhausts to prevent air entering when the fan is turned off.Heating controls vary with the nature of the heating medium.Duct heaters are generally furnished with manufacturer-installedsafety controls. Steam or hot-water heating

23、 coils require a motor-ized valve for heating control.Time clock control can limit unnecessary HVAC operation.Unoccupied reset controls should be provided in conjunction withtimed control.Maintenance. To protect the initial investment and ensure max-imum efficiency, maintenance of air-conditioning u

24、nits in smallstores should be provided by a reliable service company on a yearlybasis. The maintenance agreement should clearly specify responsi-bility for filter replacements, lubrication, belts, coil cleaning,adjustment of controls, refrigeration cycle maintenance, replace-ment of refrigerant, pum

25、p repairs, electrical maintenance, winteriz-ing, system start-up, and extra labor required for repairs.Improving Operating Cost. Outdoor air economizers can re-duce the operating cost of cooling in most climates. They are gen-erally available as factory options or accessories with roof-mountedunits.

26、 Increased exterior insulation generally reduces operating en-ergy requirements and may in some cases allow the size of installedequipment to be reduced. Most codes now include minimum re-quirements for insulation and fenestration materials. The AdvancedEnergy Design Guide for Small Retail Buildings

27、 (ASHRAE 2006)provides additional energy savings suggestions.3. DISCOUNT, BIG-BOX, AND SUPERCENTER STORESLarge discount, big-box, and supercenter stores attract customerswith discount prices. These stores typically have high-bay fixturedisplays and usually store merchandise in the sales area. They f

28、ea-ture a wide range of merchandise and may include such diverseareas as a food service area, auto service area, supermarket, phar-macy, bank, and garden shop. Some stores sell pets, including fishand birds. This variety of activity must be considered in designingthe HVAC systems. The design and app

29、lication suggestions forsmall stores also apply to discount stores.Each specific area is typically treated as a traditional stand-alonefacility would be. Conditioning outdoor air for all areas must beconsidered to limit the introduction of excess moisture that willmigrate to the freezer aisles of a

30、grocery area.Hardware, lumber, furniture, etc., is also sold in big-box facilities.A particular concern in this type of facility is ventilation for mer-chandise and material-handling equipment, such as forklift trucks.In addition, areas such as stockrooms, rest rooms, break rooms,offices, and specia

31、l storage rooms for perishable merchandise mayrequire separate HVAC systems or refrigeration.Load DeterminationOperating economics and the spaces served often dictate insidedesign conditions. Some stores may base summer load calculationson a higher inside temperature (e.g., 80F db) but then set the

32、ther-mostats to control at 72 to 75F db. This reduces the installedequipment size while providing the desired inside temperaturemost of the time.Heat gain from lighting is not uniform throughout the entire area.For example, jewelry and other specialty displays typically havelighting heat gains of 6

33、to 8 W per square foot of floor area, whereasthe typical sales area has an average value of 2 to 4 W/ft2. For stock-rooms and receiving, marking, toilet, and rest room areas, a value of2 W/ft2may be used. When available, actual lighting layouts ratherthan average values should be used for load compu

34、tation.ASHRAE Standards 62.1 and 90.1 provide data and populationdensity information to be used for load determination. Chapter 33 ofthis volume has specific information on ventilation systems forkitchens and food service areas. Ventilation and outdoor air must beprovided as required in ASHRAE Stand

35、ard 62.1 and local codes.Data on the heat released by special merchandising equipment,such as amusement rides for children or equipment used for prepar-ing speciality food items (e.g., popcorn, pizza, frankfurters, ham-burgers, doughnuts, roasted chickens, cooked nuts, etc.), should beobtained from

36、the equipment manufacturers.Design ConsiderationsHeat released by installed lighting is often sufficient to offset thedesign roof heat loss. Therefore, interior areas of these stores needcooling during business hours throughout the year. Perimeter areas,especially the storefront and entrance areas,

37、may have highly vari-able heating and cooling requirements. Proper zone control andHVAC design are essential. Location of checkout lanes in the store-front or entrance areas makes proper environmental zone controleven more important.System Design. The important factors in selecting discount, big-box

38、, and supercenter store air-conditioning systems are (1) installa-tion costs, (2) floor space required for equipment, (3) maintenancerequirements, (4) equipment reliability, and (5) simplicity of con-trol. Roof-mounted units are most commonly used.Air Distribution. The air supply for large interior

39、sales areasshould generally be designed to satisfy the primary coolingrequirement. For perimeter areas, the variable heating and cool-ing requirements must be considered.Because these stores require high, clear areas for display andrestocking, air is generally distributed from heights of 14 ft andgr

40、eater. Air distribution at these heights requires high dischargevelocities in the heating season to overcome the buoyancy of hot air.This discharge air velocity creates turbulence in the space andinduces airflow from the ceiling area to promote complete mixing.Space-mounted fans, and radiant heating

41、 at the perimeter, entranceheaters, and air curtains may be required.Control. Because the controls are usually operated by personnelwho have little knowledge of air conditioning, systems should bekept as simple as possible while still providing the required func-tions. Unitary equipment is typically

42、 available with manufacturer-supplied controls for easy installation and operation.Automatic dampers should be placed in outdoor air inlets and inexhausts to prevent air entering when the fan is turned off.Heating controls vary with the nature of the heating medium.Duct heaters are generally furnish

43、ed with manufacturer-installedsafety controls. Steam or hot-water heating coils require a motor-ized valve for heating control.Time clock control can limit unnecessary HVAC operation.Unoccupied reset controls should be provided in conjunction withtimed control.Maintenance. Most stores do not employ

44、trained HVAC main-tenance personnel; they rely instead on service contracts with eitherthe installer or a local service company. (See the section on SmallStores).Improving Operating Cost. See the section on Small Stores.Retail Facilities 2.34. SUPERMARKETSLoad DeterminationHeating and cooling loads

45、should be calculated using the meth-ods outlined in Chapter 18 of the 2013 ASHRAE HandbookFun-damentals. In supermarkets, space conditioning is required both forhuman comfort and for proper operation of refrigerated displaycases. The air-conditioning unit should introduce a minimum quan-tity of outd

46、oor air, either the volume required for ventilation basedon ASHRAE Standard 62.1 or the volume required to maintainslightly positive pressure in the space, whichever is larger.Many supermarkets are units of a large chain owned or operatedby a single company. The standardized construction, layout, an

47、dequipment used in designing many similar stores simplify loadcalculations.It is important that the final air-conditioning load be correctlydetermined. Refer to manufacturers data for information on total heatextraction, sensible heat, latent heat, and percentage of latent to totalload for display c

48、ases. Engineers report considerable fixture heatremoval (case load) variation as the relative humidity and temperaturevary in comparatively small increments. Relative humidity above55% substantially increases the load; reduced absolute humidity sub-stantially decreases the load, as shown in Figure 1

49、. Trends in storedesign, which include more food refrigeration and more efficientlighting, reduce the sensible component of the load even further. To calculate the total load and percentage of latent and sensibleheat that the air conditioning must handle, the refrigerating effectimposed by the display fixtures must be subtracted from the build-ings gross air-conditioning requirements (Table 1).Modern supermarket designs have a high percentage of closedrefrigerated display fixtures. These vertical cases have large glassdisplay doors and greatly reduce the problem of latent and sensibl