Simplified Laboratory Energy Cost Calculations - …

1 Fact Sheet No. 4 Simplified Laboratory EnergyCost CalculationsOur clients often ask, what is the yearly cost to condition one CFM of air? This is an important figure to know if youare attempting to predict Energy usage for a new facility or evaluate the economics of engineering modifications to anexisting Laboratory such as heat recovery systems or fume hood face velocity controls. You can easily calculate ap-proximate costs if you know four things: Heating Degree Days Cooling Degree Days Average Electrical Costs Average Natural Gas or Steam CostsFACTS:The costs to condition a CFM ofair may be divided into five majorcategories: heating, cooling, fluidmoving, humidification and accurately predict these costs,many consultants simulate thebuilding, mechanical systems andthe weather using a computermodel.

2 This type of accurateanalysis is recommended whendesigning a new facility in order tosize the mechanical equipmentand determine power distributionand emergency generating ca-pacity. If, however you just need arelatively close and conservativefigure then there is a simpler wayof calculating Energy costs. It util-izes the first three componentsmentioned above, heating, cool-ing and fluid moving, since thesecan be easily approximated usingsimple formulae and data which iseasy to data may be obtainedeither through the public library inthe reference section under theheading local climatological dataor directly through the NationalOceanic and Atmospheric Ad-ministration, Department ofCommerce, National ClimaticData Center, Federal Building,Eq.

3 : Heating CostsUsing natural gas as the fuel in either direct-fired equipment or in a steam boilerand assum ing an 80% efficiency yields the following:CostHTG DDHTG 65 F DayYr EGAS $CCF BtuHr CFM F 24 HrDay CCF 1x105 BtuCombining terms:CostHTG DDHTG 65 F DayYr EGAS $CCF CCFDay CFM F $CFM YrEq. : Heating CostsUsing steam as the heat source yields the following:CostHTG DDHTG 65 F DayYr ESTEAM $1000 Lb BtuHr CFM F 24 HrDay 1000 Lb 1x106 BtuCombining terms:CostHTG DDHTG 65 F DayYr ESTEAM $1000 Lb .026 LbDay CFM F $CFM YrWhere:DDHTG 65 = Heating Degree Days, 65 F Average Natural Gas CostsESTEAM= Average Steam CostsEq. 2.: Cooling CostsUsing electricity as the power source for a mecanical refrigeration system operaing ata of yields the following:CostCLG DDCLG 65 F DayYr EELECT $KwH BtuHr CFM F 24 HrDay KwH BtuCombining Terms:CostCLG DDCLG 65 F DayYr EELECT $KwH.

4 0196 KwHDay CFM F $CFM Coefficient of Performance of the mechanical refrigeration. Btu of Cooling / Btu of Energy Input (dimensionless)DDCLG 65 = Cooling Degree Days, 65 F Average Electrical CostsAsheville, NC. Utility costs can beobtained through your local utility, orin the case of a large facility, yourplant engineering or power first step is to calculate theheating costs. If your heating sys-tem uses natural gas apply equation1. A., if it uses steam apply next step is to calculate thecooling costs. See equation third step is to calculate thefluid moving costs. Use equation final step is to to combine all ofthese to get the total cost . Seeequation example, in Midland, Michiganwhich has 6847 heating degreedays, 555 cooling degree days, anaverage natural gas cost of$ , and an average electri-cal cost of $ will yield anannual cost of $ to conditionone CFM of air per year.

5 This isshown in example :Note that these formulas are, insome cases fairly conservative be-cause they only estimate sensibleheating and cooling loads and donot take into account latent heat inthe form of dehumidification andhumidification. Actual costs in mostapplications and locations will behigher. In hot and humid locations(Florida, Louisiana, etc.) requiringextensive dehumidification and inextremely cold areas (Minnesota,etc.) which require significant hu-midification this method may yieldresults as much as 25-30% lowerthan :The average four foot benchtopfume hood consumes approximately800 CFM of air from the laboratoryspace. In the above example, thisone hood, operated in a constantvolume fashion, would cost over$1,800 per year to operate.

6 In amedium sized educational or re-search Laboratory facility with 100fume hoods of different sizes, theyearly Energy costs to operate thefacility can exceed a quarter of amillion are many ways to conserveenergy in laboratories without sacri-ficing safety. For example, heat re-covery and variable air volume labo-ratory airflow controls can result in asavings of more than 50% of yourannual Energy consumption andcosts. An experienced laboratoryconsultant can assist you whenbuilding a new facility, renovating anexisting facility or examining the op-tions to reduce your operating MissionofSAFELAB Corporationis to glorify will do this by providing spe-cialized engineering and industrialhygiene services to its CUSTOMERS which meet their needs, protect theirhealth, productivity and us to assist you with: Laboratory Planning, Safety,and Design Consulting Laboratory Fume Hood Testingand Evaluation Services Laboratory Fume Hood Data-base & Documentaion Services Laboratory Fume Hood Opera-tor Training Services Industrial Ventilation Consulting Indoor Air Quality Consulting forIndustry, Commercial Buildings,and HospitalsContact Us.

7 SAFELAB Corporation5350 West 79th StreetIndianapolis, Indiana : 1-888-SAFELAB(1-888-753-3522)1-317-872-6 600E-Mail: 3.: Fluid Moving CostsUsing electricity as the power source for supply fans, exhaust fans, air-cooled conden-ser fans or cooling tower fans, and hot/chilled water pumps for a typical laboratorymechanical system yields the following:CostFLUID MOVING EELECT $KwH .746 KwHp HpCFM 8760 HrYrCombining Terms:CostFLUID MOVING EELECT $KwH KwHCFM Yr $CFM YrWhere:EELECT= Average Electrical CostsEq. 4.: Total CostsCostTOTAL CostHTG + CostCLG + CostFLUID MOVINGE xample 1. Total CostCostTOTAL 6847 F DayYr $CCF CCFDay CFM F= $ (Heating) + 555 F DayYr $KwH .0196 KwHDay CFM F= $ (Cooling) + $KwH KwHCFM Yr= $ (Fluid Mvg)= $CFM Yr