ASHRAE HVAC APPLICATIONS IP CH 37-2015 OWNING AND OPERATING COSTS.pdf

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1、37.1CHAPTER 37OWNING AND OPERATING COSTSOwning Costs 37.1Operating Costs 37.4Maintenance Costs 37.7Refrigerant Phaseouts. 37.8Other Issues. 37.8Economic Analysis Techniques . 37.9Symbols . 37.13WNING and operating cost information for the HVAC systemOshould be part of the investment plan of a facili

2、ty. This infor-mation can be used for preparing annual budgets, managing assets,and selecting design options. Table 1 shows a representative formthat summarizes these costs.A properly engineered system must also be economical, butthis is difficult to assess because of the complexities surroundingeff

3、ective money management and the inherent difficulty of pre-dicting future operating and maintenance expenses. Complex taxstructures and the time value of money can affect the final engi-neering decision. This does not imply use of either the cheapestor the most expensive system; instead, it demands

4、intelligentanalysis of financial objectives and the owners requirements.Certain tangible and intangible costs or benefits must also beconsidered when assessing owning and operating costs. Localcodes may require highly skilled or certified operators for spe-cific types of equipment. This could be a s

5、ignificant cost over thelife of the system. Similarly, intangible items such as aesthetics,acoustics, comfort, safety, security, flexibility, and environmen-tal impact may vary by location and be important to a particularbuilding or facility.1. OWNING COSTSThe following elements must be established

6、to calculate annualowning costs: (1) initial cost, (2) analysis or study period, (3) interestor discount rate, and (4) other periodic costs such as insurance, prop-erty taxes, refurbishment, or disposal fees. Once established, theseelements are coupled with operating costs to develop an economicanal

7、ysis, which may be a simple payback evaluation or an in-depthanalysis such as outlined in the section on Economic Analysis Tech-niques.Initial CostMajor decisions affecting annual owning and operating costs forthe life of the building must generally be made before completingcontract drawings and spe

8、cifications. To achieve the best perfor-mance and economics, alternative methods of solving the engineer-ing problems peculiar to each project should be compared in theearly stages of design. Oversimplified estimates can lead to substan-tial errors in evaluating the system. The evaluation should lea

9、d to a thorough understanding of instal-lation costs and accessory requirements for the system(s) under con-sideration. Detailed lists of materials, controls, space and structuralrequirements, services, installation labor, and so forth can be preparedto increase accuracy in preliminary cost estimate

10、s. A reasonable esti-mate of capital cost of components may be derived from cost recordsof recent installations of comparable design or from quotationsThe preparation of this chapter is assigned to TC 7.8, Owning and Operat-ing Costs.Table 1 Owning and Operating Cost Data and SummaryOWNING COSTSI. I

11、nitial Cost of System _II. Periodic CostsA. Income taxes _B. Property taxes _C. Insurance _D. Rent _E. Other periodic costs _Total Periodic Costs _III. Replacement Cost _IV. Salvage Value _Total Owning Costs _OPERATING COSTSV. Annual Utility, Fuel, Water, etc., CostsA. Utilities1. Electricity _2. Na

12、tural gas _3. Water/sewer _4. Purchased steam _5. Purchased hot/chilled water _B. Fuels1. Propane _2. Fuel oil _3. Diesel _4. Coal _C. On-site generation of electricity _D. Other utility, fuel, water, etc., costs _Total _VI. Annual Maintenance Allowances/CostsA. In-house labor _B. Contracted mainten

13、ance service _C. In-house materials _D. Other maintenance allowances/costs (e.g., water treatment)_Total _VII. Annual Administration Costs _Total Annual Operating Costs _TOTAL ANNUAL OWNING AND OPERATING COSTS _37.2 2015 ASHRAE HandbookHVAC Applicationssubmitted by manufacturers and contractors, or

14、by consulting com-mercially available cost-estimating guides and software. Table 2shows a representative checklist for initial costs.Analysis PeriodThe time frame over which an economic analysis is performedgreatly affects the results. The analysis period is usually determinedby specific objectives,

15、 such as length of planned ownership or loanrepayment period. However, as the length of time in the analysisperiod increases, there is a diminishing effect on net present-valuecalculations. The chosen analysis period is often unrelated to theequipment depreciation period or service life, although th

16、ese factorsmay be important in the analysis.Service LifeFor many years, this chapter included estimates of service lives forvarious HVAC system components, based on a survey conducted in1976 under ASHRAE research project RP-186 (Akalin 1978).These estimates have been useful to a generation of practi

17、tioners,but changes in technology, materials, manufacturing techniques,and maintenance practices now call into question the continuedvalidity of the original estimates. Consequently, ASHRAE researchproject TRP-1237 developed an Internet-based data collection tooland database on HVAC equipment servic

18、e life and maintenancecosts, to allow equipment owning and operating cost data to be con-tinually updated and current. The database was seeded with infor-mation gathered from a sample of 163 commercial office buildingslocated in major metropolitan areas across the United States.Abramson et al. (2005

19、) provide details on the distribution of build-ing size, age, and other characteristics. Table 3 presents estimates ofmedian service life for various HVAC components in this sample.Median service life in Table 3 is based on analysis of survivalcurves, which take into account the units still in servi

20、ce and the unitsreplaced at each age (Hiller 2000). Conditional and total survivalrates are calculated for each age, and the percent survival over timeis plotted. Units still in service are included up to the point where theage is equal to their current age at the time of the study. After thatpoint,

21、 these units are censored (removed from the population).Median service life in this table indicates the highest age at whichthe survival rate remains at or above 50% while the sample size is 30or more. There is no hard-and-fast rule about the number of unitsneeded in a sample before it is considered

22、 statistically large enoughto be representative, but usually the number should be larger than 25to 30 (Lovvorn and Hiller 2002). This rule-of-thumb is used becauseeach unit removal represents greater than a 3% change in survivalrate as the sample size drops below 30, and that percentage increasesrap

23、idly as the sample size gets even smaller.The database initially developed and seeded under research proj-ect TRP-1237 (Abramson et al. 2005) is now available online,providing engineers with equipment service life and annual mainte-nance costs for a variety of building types and HVAC systems. Thedat

24、abase can be accessed at www.ashrae.org/database.As of the end of 2009 this database contained more than300 building types, with service life data on more than 38,000 piecesof equipment.The database allows users to access up-to-date information todetermine a range of statistical values for equipment

25、 owning andoperating costs. Users are encouraged to contribute their own ser-vice life and maintenance cost data, further expanding the utility ofthis tool. Over time, this input will provide sufficient service lifeand maintenance cost data to allow comparative analysis of manydifferent HVAC systems

26、 types in a broad variety of applications.Data can be entered by logging into the database and registering,which is free. With this, ASHRAE is providing the necessary meth-ods and information to assist in using life-cycle analysis techniquesto help select the most appropriate HVAC system for a speci

27、ficapplication. This system of collecting data also greatly reduces thetime between data collection and when users can access the infor-mation.Figure 1 presents the survival curve for centrifugal chillers,based on data in Abramson et al. (2005). The point at which survivalrate drops to 50% based on

28、all data in the survey is 31 years. How-ever, because the sample size drops below the statistically relevantnumber of 30 units at 25 years, the median service life of centrifugalchillers can only be stated with confidence as 25 years.Table 2 Initial Cost ChecklistEnergy and Fuel Service CostsFuel se

29、rvice, storage, handling, piping, and distribution costsElectrical service entrance and distribution equipment costsTotal energy plantHeat-Producing EquipmentBoilers and furnacesSteam-water convertersHeat pumps or resistance heatersMakeup air heatersHeat-producing equipment auxiliariesRefrigeration

30、EquipmentCompressors, chillers, or absorption unitsCooling towers, condensers, well water suppliesRefrigeration equipment auxiliariesHeat Distribution EquipmentPumps, reducing valves, piping, piping insulation, etc.Terminal units or devicesCooling Distribution EquipmentPumps, piping, piping insulati

31、on, condensate drains, etc.Terminal units, mixing boxes, diffusers, grilles, etc.Air Treatment and Distribution EquipmentAir heaters, humidifiers, dehumidifiers, filters, etc.Fans, ducts, duct insulation, dampers, etc.Exhaust and return systemsHeat recovery systemsSystem and Controls AutomationTermi

32、nal or zone controlsSystem program controlAlarms and indicator systemEnergy management systemBuilding Construction and AlterationMechanical and electric spaceChimneys and fluesBuilding insulationSolar radiation controlsAcoustical and vibration treatmentDistribution shafts, machinery foundations, fur

33、ringTable 3 Median Service LifeEquipment TypeMedian Service Life, YearsTotalNo. ofUnitsNo. ofUnits ReplacedDX air distribution equipment 24 1907 284Chillers, centrifugal 25 234 34Cooling towers, metal 22 170 24Boilers, hot-water, steel gas-fired 22 117 24Controls, pneumatic 18 101 25electronic 7 68

34、6Potable hot-water heaters, electric 21 304 36Owning and Operating Costs 37.3Table 4 compares the estimates of median service life inAbramson et al. (2005) with those developed with those in Akalin(1978). Most differences are on the order of one to five years.Estimated service life of new equipment

35、or components of systemsnot listed in Table 3 or 4 may be obtained from manufacturers, associ-ations, consortia, or governmental agencies. Because of the proprietarynature of information from some of these sources, the variety of criteriaused in compiling the data, and the diverse objectives in diss

36、eminatingthem, extreme care is necessary in comparing service life from differentsources. Designs, materials, and components of equipment listed inTables 3 and 4 have changed over time and may have altered the esti-mated service lives of those equipment categories. Therefore, establish-ing equivalen

37、t comparisons of service life is important.As noted, service life is a function of the time when equipment isreplaced. Replacement may be for any reason, including, but not lim-ited to, failure, general obsolescence, reduced reliability, excessivemaintenance cost, and changed system requirements (e.

38、g., buildingcharacteristics, energy prices, environmental considerations).Service lives shown in the tables are based on the age of the equip-ment when it was replaced, regardless of the reason it was replaced.Locations in potentially corrosive environments and uniquemaintenance variables affect ser

39、vice life. Examples include the fol-lowing:Coastal and marine environments, especially in tropical loca-tions, are characterized by abundant sodium chloride (salt) that iscarried by sea spray, mist, or fog.Many owners require equipment specifications stating thatHVAC equipment located along coastal

40、waters will have corrosion-resistant materials or coatings. Design criteria for systems installedunder these conditions should be carefully considered.Industrial applications provide many challenges to the HVACdesigner. It is very important to know if emissions from the indus-trial plant contain pro

41、ducts of combustion from coal, fuel oils, orreleases of sulfur oxides (SO2, SO3) and nitrogen oxides (NOx)into the atmosphere. These gases typically accumulate and returnto the ground in the form of acid rain or dew.Not only is it important to know the products being emittedfrom the industrial plant

42、 being designed, but also the adjacentupwind or downwind facilities. HVAC system design for a plantlocated downwind from a paper mill requires extraordinary cor-rosion protection or recognition of a reduced service life of theHVAC equipment.Table 4 Comparison of Service Life EstimatesEquipment ItemM

43、edian Service Life, YearsEquipment ItemMedian Service Life, YearsEquipment ItemMedian Service Life, YearsAbramsonet al. (2005)Akalin (1978)Abramsonet al. (2005)Akalin (1978)Abramsonet al. (2005)Akalin (1978)Air Conditioners Air Terminals Condensers Window unit N/A* 10 Diffusers, grilles, and registe

44、rs N/A* 27 Air-cooled N/A 20Residential single or split package N/A* 15 Induction and fan-coil units N/A* 20 Evaporative N/A* 20Commercial through-the-wall N/A* 15 VAV and double-duct boxes N/A* 20 InsulationWater-cooled package 24 15 Air washers N/A* 17 Molded N/A* 20Heat pumps Ductwork N/A* 30 Bla

45、nket N/A* 24Residential air-to-air N/A* 15bDampers N/A* 20 PumpsCommercial air-to-air N/A* 15 Fans N/A* Base-mounted N/A* 20Commercial water-to-air 24 19 Centrifugal N/A* 25 Pipe-mounted N/A* 10Roof-top air conditioners Axial N/A* 20 Sump and well N/A* 10Single-zone N/A* 15 Propeller N/A* 15 Condens

46、ate N/A* 15Multizone N/A* 15 Ventilating roof-mounted N/A* 20 Reciprocating engines N/A* 20Boilers, Hot-Water (Steam) Coils Steam turbines N/A* 30Steel water-tube 22 24 (30) DX, water, or steam N/A* 20 Electric motors N/A* 18Steel fire-tube 25 (25) Electric N/A* 15 Motor starters N/A* 17Cast iron N/

47、A* 35 (30) Heat Exchangers Electric transformers N/A* 30Electric N/A* 15 Shell-and-tube N/A* 24 ControlsBurners N/A* 21 Reciprocating compressors N/A* 20 Pneumatic N/A* 20Furnaces Packaged Chillers Electric N/A* 16Gas- or oil-fired N/A* 18 Reciprocating N/A* 20 Electronic N/A* 15Unit heaters Centrif

48、ugal 25 23 Valve actuatorsGas or electric N/A* 13 Absorption N/A* 23 Hydraulic N/A* 15Hot-water or steam N/A* 20 Cooling Towers Pneumatic N/A* 20Radiant heaters Galvanized metal 22 20 Self-contained 10Electric N/A*10Wod N/A*20Hot-water or steam N/A* 25 Ceramic N/A* 34*N/A: Not enough data yet in Abr

49、amson et al. (2005). Note that data from Akalin (1978) for these categories may be outdated and not statistically relevant. Use these data with cau-tion until enough updated data are accumulated in Abramson et al.Fig. 1 Survival Curve for Centrifugal ChillersBased on data in Abramson et al. (2005)37.4 2015 ASHRAE HandbookHVAC ApplicationsUrban areas generally have high levels of automotive emissionsas well as