Consulting-Specifying Engineer - June 2008 - (Page 43)

HVAC equipment selection Typically, two predominant types of HVAC design are used in retail design. Unitary rooftop equipment is the most common type of equipment and design strategy. There are several benefits to this type of system for a retail real estate developer. Packaged equipment offers a single solution to HVAC for a wide variety of applications with little adjustment required to accommodate different styles of retail outlets. This type of equipment also tends to be the most economical solution. These two factors often make package unitary rooftop equipment the design solution of choice for retail HVAC design. Rooftop HVAC equipment offers simplified design approach when routing ductwork to and from conditioned spaces when roof and plenum space is not an issue. This approach incurs a lower initial cost to the developer and provides for quicker construction schedules. This type of equipment is less efficient, requires more maintenance, and typically has a shorter lifecycle. The cost associated with rooftop equipment often is passed to the leasing tenant as part of the lease, and this further reduces the initial cost of the project. Therefore, the decision to use rooftop equipment must be weighed against the priorities of the developer and the project as a whole. The other dominant approach to a retail outlet’s HVAC design is the central plant concept. This system has hydronic components such as chilled water, hot water, and heat pump loops. Significant advantages for this type of design strategy exist when focusing on the efficiency, controllability, and flexibility of an HVAC system. Because the upfront capital investment costs are higher, the owner should focus on the extended energy efficiency and operational characteristics of the development in order to make that increased financial commitment. A central energy plant can lower operational costs of large retail developments. The ability to maintain occupant comfort and improve the patron experience is enhanced through greater control of system components. The initial cost may be much higher, and most of this burden for L TIA N EN TIO SID UC RE STR RY ON XU C LU DER UN ON W CTIO08 E T TRU 20 AS NS LL PHER CO G FA D ENIN UN OP (P ) PARKING GARAGE ABOVE RETAIL PARKING GARAGE ABOVE RETAIL VIL EN LA GE GR EE N VIL LA G RE EG UN ON W CTIO E T TRU G AS NS ASIN PHER CO LE W D NO Jew ele rs RESTAURANT D EN UN OP ON W CTIO08 E T TRU 20 AS NS LL PHER CO G FA IN Figure 1: An example of a leasing plan from the leasing agent for a town center retail development shows expected tenants and the stage of commitment for each. Source: Graef, Anhalt, Schloemer, & Assocs. Inc., used with permission from Opus North Corp. Inc. from the Burr Ridge Village Center Development, Burr Ridge, Ill. (P ) infrastructure costs must be borne by the developer. This offset of operational costs and increased life expectancy of equipment can be balanced against developers’ higher initial costs to determine the right system for the facility. Other factors to consider are the flexibility of the system to accommodate remodeling and available space for back-of-house systems, such as economizer duct shafts and relief air systems. Sub-metering for success Incorporating sub-metering into retail outlet design for utilities, such as natural gas, electricity, water, and sewer, is a decision that cannot be made by the engineer or architect alone. This decision needs input from the developer, real estate personnel, engineers, architects, and utility contacts. To understand what is required for utility metering, the requirements of the local utility company must be investigated with respect to the anticipated distribution scheme of the engineering design. The additional cost of construction must be balanced against the potential benefit to the developer for easier billing tabulation of leased space utilities. In some cases, local utilities might have requirements for restrictions against submetering: Sub-metering strategies for water might include meters located in each tenant space, and the developer is responsible for charging tenants for the utility service. In the event that a dollar/square foot cost is written into the lease of a space for water service, this could be interpreted as water utility service and therefore would require regulation by the appropriate governing body. This reinforces the fact that investigation of local requirements of code and utility requirements are incredibly important. Individual metering of electrical and natural gas utilities offer more incentive to developers in the form of greatly simplified billing for these services. In some cases, these utilities might even be billed directly to the lessee of the space by the utility so the developing company can be removed from this paper trail. In this case, the benefit to eliminate this administrative cost can be easily weighed against the additional installation cost and educated judgments can be made. The decision should be made as early in the design process as possible to be incorporated into the “Article C” documents used by the real estate personnel leasing spaces and provide clear direction for designers of energy distribution systems. Consulting-Specifying Engineer • JUNE 2008 43

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Consulting-Specifying Engineer - June 2008 Contents Viewpoint Letters News M/E Roundtable No Gambling Allowed on Smoke Control in Las Vegas Be Prepared: Hospital Protections for Catastrophic Events Ready for Retail Commissioning Documents: Necessary Evil Codes & Standards Codes & Standards Case Study Equipment Lifecycles New Products Advertiser Index Green Space

Consulting-Specifying Engineer - June 2008

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