Dehumidifiers: A Major Consumer of Residential Electricity

Transcription

1 Dhumidifirs: A Major Consumr of Rsidntial Elctricity Laurn Mattison and Dav Korn, Th Cadmus Group, Inc. ABSTRACT An stimatd 19% of U.S. homs hav dhumidifirs, and thy can account for a substantial portion of rsidntial nrgy us. Annual lctricity consumption by dhumidifirs can b 1, kwh or mor, twic as much as an ENERGY STAR rfrigrator uss. This study masurd powr, watr rmoval rats and ambint humidity for 21 rsidntial dhumidifirs in th Northast and Mid-Atlantic rgions ovr a thr month priod in 211. Masuring watr rmoval rats allowd for calculation of th nrgy factor (watr rmovd pr unit lctricity, a mtric rarly capturd in fild opration. Th analysis shows fficincy, oprating hours and lctricity consumption. Ky findings includ that fild fficincis of many units ar quit low and th humidity controls on som dhumidifirs do not function proprly. Dhumidifir Us and Efficincy A rcnt rport stimats that 19% of U.S. housholds hav at last on dhumidifir (Applianc Magazin 28, 7. Dhumidifir capacity is ratd by th volum of watr that can b rmovd from th air, usually masurd in pints pr day. Most rsidntial units hav ratd capacitis btwn 25 and 75 pints/day with som mor than 1 pints/day. Most dhumidifirs sold in rcnt yars allow th usr to adjust th rlativ humidity (RH stpoint (oftn slctd in trms of % RH, somtims othr options such as low/mdium/high and th fan spd. Efficincy Ratings Efficincy of dhumidifirs is ratd in trms of nrgy factor (EF, th volum of watr rmovd from th air pr unit of nrgy consumd, masurd in litrs pr kilowatt-hour (L/kWh. A Fdral standard rgulats th minimum EF of dhumidifirs manufacturd in th U.S., with a scal of EF rquirmnts basd on unit capacity, and ENERGY STAR provids a spcification for high fficincy dhumidifirs. Th currnt ENERGY STAR spcification for dhumidifirs (V2.1 has bn in ffct sinc 26, and EPA stimatd that 82% of dhumidifirs sold in 29 mt th currnt ENERGY STAR rquirmnts (EPA 211a. In Octobr 212, both a rvisd Fdral standard and rvisd ENERGY STAR spcification (V3. will go into ffct. Tabl 1 shows ths currnt and futur standard. 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-24

2 Tabl 1. Efficincy Standards for Dhumidifirs, Enrgy Factor (L/kWh Currnt Effctiv Octobr 212 Fdral standard ENERGY STAR V2.1 Fdral standard ENERGY STAR V3. 25 pints/day pints/day 1.2 > 25 to > 25 to pints/day 1.35 > 35 to > 35 to > 35 to < 75 pints/day 1.85 > 45 to > 45 to > 54 to < > 54 to < > 54 to < to Sourc: NARA 21 & EPA 211b Rsarch Mthodology Study Sampl & Mtring Priod Th Cadmus Group mtrd 21 dhumidifirs oprating in 19 homs in Massachustts, Nw York, Maryland and Virginia. Mtring of ach unit bgan btwn mid Sptmbr and arly Octobr 211 and continud for on to 12 wks. In most cass, mtring continud until th dhumidifir was turnd off for th sason, or for at last two months for th units that run yar round. W intrviwd participants about thir usag pattrns and askd thm to run thir dhumidifirs as thy normally would throughout th mtring priod. Th timing of this study did not allow for masurmnt of pak opration xpctd during th spring and summr. Thrfor annual projctions basd on this study ar xpctd to b consrvativ stimats of dhumidifir opration. Mtring Approach Powr mtrs masurd th wattag of th dhumidifir continuously and loggd powr in fiv-minut incrmnts. Mtrs placd nar th units masurd th ambint tmpratur and RH. W gav data collction shts and graduatd masuring buckts to participants who manually mptid thir units, and thy kpt a log of th tim and volum of watr ach tim thy mptid it. Rsarch Findings Modl Information & Configurations Tabl 2 shows th sampl of dhumidifir modls and configurations includd in th study. Dhumidifirs rangd from nw to 15 yars old, with an avrag of four yars old. Th avrag ratd capacity was 45 pints/day, with units ranging from 25 to 7 pints/day. All of th modls purchasd in th last fiv yars mt th currnt ENERGY STAR standard. Th EF rating was not availabl for th thr oldst modls, but nithr of th units oldr than fiv yars for which w had EF ratings mt th currnt ENERGY STAR lvl. All of th dhumidifirs wr usd in basmnts, a mix of finishd and unfinishd. Two participants had two units ach oprating in th sam basmnt. Six of th 21 units wr st up 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-25

3 to drain dirctly, and th rmaining 15 units ndd to hav th tub of collctd watr mptid manually. Participants usd an avrag RH stting of 5%, with a rang of 35% to 65%. Rportd fan spd sttings wr split vnly btwn low and high, with a fw participants changing thir stting during th mtring priod. A fw of th oldst modls didn t offr a choic of fan spd. Usag Pattrns Tabl 2. Dhumidifirs in Study Ag (yars Capacity (pints/day Ratd EF (L/kWh RH Stpoint Dirct Drain or Manually Empty Continuous Empty % Drain % Empty % Empty % Empty Unknown Empty % Empty % Empty % Drain % Drain % Empty % Drain 3 Unknown Unknown 35% Empty % Empty % Drain % Empty % Empty % Empty 1 25 Unknown Mdium Empty 12 4 Unknown Unknown Empty 15 5 Unknown Mdium Drain About half of participants lav thir units on yar round, and th othr half run thm sasonally for a priod btwn spring and fall. Most participants who us thir dhumidifirs sasonally turnd thm off in Octobr or Novmbr, and thy rportd that thy turn thm back on btwn April and July. Th avrag rportd opration was 8 months/yar. Most of th participants without dirct drains waitd until th tub was full to mpty thir dhumidifir. Som chckd thir units at last onc a day, whil othrs only chckd and mptid thir dhumidifirs occasionally, so th tub may b full for hours or days bfor bing mptid. 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-26

4 Most participants lft thir units on throughout thir mtring priod. A fw popl turnd thir units on and off manually, with rportd rasons including saving nrgy and rducing nois whn thy ar nar th unit. Powr Standby powr. Mtr data showd that 1 units drw no powr whn not oprating, whil th othr 11 drw standby powr btwn.4 and 1.9 Watts. Units using standby powr rangd from nw to ight yars old. On usr obsrvd that th fan opratd continuously on his nw unit aftr raching th humidity stpoint, so h turnd th unit off manually to rduc nrgy consumption. In Dcmbr 21, th U.S. Dpartmnt of Enrgy proposd to amnd th tst procdur and nrgy consumption quations for dhumidifirs to includ th masurmnt of nrgy us in standby and off mods (NARA 21, Activ powr. Th avrag powr whn running, xcluding standby powr, was 459 Watts. Figur 1 shows th avrag activ mod powr and ag of ach unit. A linar rgrssion shows a limitd corrlation btwn unit ag and avrag powr. Whil ag may affct dhumidifir powr, thr ar svral othr xpctd factors including unit fficincy, usr sttings and ambint conditions. Th maximum powr mtrd for ach unit rangd from 375 to 964 Watts, as shown in Figur 2. A linar rgrssion shows a limitd rlationship btwn unit ag and maximum powr. Figur 1. Avrag Activ Powr Vs. Unit Ag 1, (W r w o P tiv c A g ra v A R² = Unit Ag (yars Units Ratd Undr 5 pints/day Units Ratd At Last 5 pints/day All Units 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-27

5 Figur 2. Maximum Powr Vs. Unit Ag 1, (W r w o P m u im x a M R² = Unit Ag (yars Units Ratd Undr 5 pints/day Units Ratd At Last 5 pints/day All Units Watr Rmoval Participants who manually mptid thir units loggd th tim and masurd th watr volum ach tim. Th watr rmoval avragd 4.9 pints/day for ths units, with a wid rang from.2 to 12 pints/day. A limiting factor in watr rmoval was th nd to manually mpty ths units. Whil th ratd capacity of manually mptid dhumidifirs in th study rangd from 25 to 7 pints/day, thir tub volums masurd btwn 6 and 24 pints. Most tub volums wr lss than half th ratd unit capacity, maning th units would nd to b manually mptid mor than twic pr day to provid th ratd watr rmoval. Dpnding on unit siz and ambint conditions, som units may not nd to run at ratd capacity to provid th dsird rsults, but usrs should b awar of this potntial limitation and th importanc of tub volum whn purchasing dhumidifirs. Othr factors affcting th amount of watr rmovd includ ambint conditions and usr sttings. Oprating Hours During th mtring priod, th avrag runtim (not including tim drawing standby powr was 8.9 hours/day, for an avrag duty cycl of 37%. At that rat, annual runtim would b 2,16 hours, basd on th 8 months/yar avrag discussd abov. Th actual annual oprating hours ar xpctd to b highr bcaus this study did not includ mtring during th tim of yar whn dhumidifir opration is xpctd to b at its pak. This rsult indicats 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-28

6 highr dhumidifir oprating hours than th 1,62 stimatd in a frquntly citd 1998 Arthur D. Littl rport (Zogg, 34. As discussd abov, opration of som units was limitd by th nd for th usr to frquntly mpty th rlativly small tub. Bcaus dirct drain units wr not limitd by tub siz, thy opratd longr hours, with avrag activ runtim of 11 hours/day for dirct drain units, compard to 8.1 hours/day for manually mptid units. During th pak oprating sason, this diffrnc would likly b gratr. Elctricity Consumption Th avrag mtrd lctricity consumption was 4.2 kwh/day. As with oprating hours, lctricity consumption was highr for dirct drain units (5.6 kwh/day than for manually mptid units (3.7 kwh/day. It is assumd that th corrsponding watr rmoval was also highr, though this study did not includ masurmnt of watr rmoval from dirct drain units. Figur 3 compars th avrag daily lctricity consumption and watr rmoval for ach of th 15 units that wr manually mptid. This graph shows a wak corrlation btwn watr rmoval and lctricity consumption. If th on outlying data point (a 12 yar old unit consuming 14.3 kwh/day wr rmovd, howvr, th R-squard valu for a linar rgrssion would incras to.47. A numbr of othr factors affct lctricity consumption, including ambint conditions, usr sttings, and fficincy of th unit. Figur 4 shows that lctricity consumption was not rlatd to ratd unit capacity. As discussd abov, no manually mptid unit rachd its ratd watr rmoval capacity in this priod, so th capacity would not b xpctd to b a major factor in opration, for thos units at last. 16 Figur 3. Avrag Daily Elctricity Us Vs. Watr Rmoval 14 y a /d h W (k ity tric c l E R² = Watr Rmovd (pints/day Units Ratd Undr 5 pints/day Units Ratd At Last 5 pints/day All Units 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-29

7 Figur 4. Avrag Daily Elctricity Us Vs. Ratd Unit Capacity y a /d h W (k ity tric c l E R² = Ratd Unit Capacity (pints/day Units Up To 5 Yars Old Units Mor Than 5 Yars Old All Units Projcting th mtrd daily lctricity consumption across th yar basd on th avrag 8 months/yar of opration xplaind abov, annual lctricity consumption would b about 1, kwh. At th 211 national avrag rsidntial lctric rat of $.118/kWh, th avrag annual oprating cost is $12 (EIA 212a. For comparison, a nw ENERGY STAR ratd rfrigrator uss about 5 kwh/yar, or 1.4 kwh/day (EPA 212c. According to th U.S. Enrgy Information Administration, th avrag houshold usd 11,496 kwh in 21 (EIA, 212b. At th avrag consumption of 1, kwh, on dhumidifir would account for approximatly 9% of th lctricity consumption in a hom. Enrgy Factor To valuat th fficincy of th dhumidifirs, w usd th masurd lctricity consumption and watr rmoval thn calculatd th actual EF for ach unit that was manually mptid. Th masurd EF rangd from.2 to 2.1 L/kWh, with an avrag of.8 L/kWh. As shown in Figur 5, th masurd EF was lowr than th ratd EF for all but two units. A 12 yar old dhumidifir, th oldst of th manually mptid units, had th lowst masurd EF at.19 L/kWh, but as shown in Figur 6, a minimal corrlation was found btwn unit ag and masurd nrgy factor. As discussd abov, EF ratings wr not availabl for thr of ths units. 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-21

8 Figur 5. Comparison of Masurd and Ratd Enrgy Factors 2.5 Figur 6. Masurd Enrgy Factor Vs. Unit Ag h W /k rs (lit r to c a F y rg n E d r u s a M R² = Unit Ag (yars Units Ratd Undr 5 pints/day Units Ratd At Last 5 pints/day All Units 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-211

9 Impact of ambint conditions on nrgy factor. EF ratings ar basd on tsting at dry-bulb tmpratur of 8 F and wt-bulb tmpratur of 69.6 F, which quats to about 6% RH at sa lvl (AHAM, 7. Mtr data showd th actual tmpratur and RH wr blow ths valus for almost all units, as xpctd sinc most units wr st to lss than 6% RH. Whn th study bgan, on of th units had just bn installd in a basmnt whr no dhumidifir had bn usd in rcnt yars, so that mtr showd RH lvls as high as 72% arly in th study. Th avrag masurd EF for that unit was 1.15, vry clos to its rating of 1.2 and on of th highst EF valus in th study. Figur 7 shows th EF and RH of this unit ovr a four-day priod shortly aftr th dhumidifir was first turnd on. Th blu lin shows that th EF starts out nar 2, wll abov th ratd fficincy, and dcrasd to 1 ovr a fw days as th basmnt humidity in th dottd grn lin dcrasd blow 6%. Th mtr masurd RH continuously, whil EF was calculatd onc or twic a day whn th usr mptid th tub. Figur 7. Enrgy Factor Varying with Rlativ Humidity h W /k rs 1.5 (lit r to c a F 1. y rg n E R la tiv H u m id ity (%. 1/4/211 1/5/211 1/6/211 1/7/211 1/8/211 Dat Masurd EF Ratd EF RH This indicats that dhumidifirs in actual oprating conditions may prform at lowr fficincy than thy would at th tst conditions usd to rat dhumidifir fficincy. Additional mtring could b prformd in th summr to compar summr oprating conditions to th tst conditions and masur EF during pak opration. 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-212

10 Accuracy of Humidity Controls To valuat th accuracy of th dhumidifir controls, w graphd RH and powr ovr tim for ach unit. Som units showd rsults tracking closly with th rportd stpoint, whil othrs showd potntially faulty controls. For xampl, Figur 8 shows opration of on unit ovr a 1 day priod. Th dhumidifir was st at 65% RH, indicatd by th straight lin, and th masurd RH is shown in th dottd grn lin. As th blu powr lin shows, th dhumidifir did not oprat during days whn th RH was consistntly abov th stpoint. This unit has bn st up to drain dirctly, so opration was not limitd by tub capacity. At tims this unit dos oprat, with an avrag of 2.4 hours/day of runtim during th mtring priod, but th data show a discrpancy btwn th RH masurd during opration and th RH stpoint. This is an xtrm cas, as th participant dscribd hr basmnt as vry wt, with puddls of standing watr. Figur 8. Dhumidifir Not Oprating Whn RH Excds Stpoint (W r w o 4 P R la tiv H u m id ity (% 1/29/211 1/31/211 11/2/211 11/4/211 11/6/211 11/8/211 Powr RH RH stpoint Conclusion This study of 21 dhumidifirs oprating in Northast and Mid-Atlantic homs showd that dhumidifirs ar nrgy intnsiv appliancs that oprat for svral months a yar in many homs. To build on this study, w plan to do additional mtring in th futur during th spring and summr months. Ky findings to dat includ: Participants rportd an avrag of 8 months/yar of dhumidifir opration. 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-213

11 Th avrag mtrd runtim was 8.9 hours/day. At 8 months/yar, th avrag unit would oprat 2,16 hours annually. Th avrag mtrd activ powr was 459 Watts. Elvn of th units drw standby powr btwn.4 and 1.9 Watts. Th avrag mtrd lctricity consumption was 4.2 kwh/day, or 1, kwh/yar basd on 8 months/yar of opration. This is qual to 9% of th lctricity consumption in an avrag hom. For th 15 manually mptid units, th avrag watr rmoval was 4.9 pints/day and th avrag EF was.8 L/kWh. Th humidity controls on som units did not function proprly, as som units did not oprat whn a sparat mtr showd ambint RH xcding th stpoint. Th masurd EF was lowr than th ratd EF for all but two units. This lowr oprating fficincy is blivd to b in part bcaus most units in this study wr oprating in spacs with lowr tmpratur and RH than th standard tst conditions. Usr opration is a ky factor in ffctivnss and nrgy consumption of dhumidifirs, including frquncy of mptying tubs for units that don t drain dirctly. Whil it is byond th scop of this study to quantify th idal watr rmoval in ach hom, watr rmoval by som dhumidifirs in th study was limitd by th nd for tubs to b manually mptid whn thy rachd capacity. Most tub volums wr lss than half th ratd unit capacity, maning th units would nd to b manually mptid mor than twic pr day, or st up to drain dirctly, to provid th ratd watr rmoval. Rfrncs Applianc Magazin st Annual Portrait of th U.S. Applianc Industry. [AHAM] Association of Hom Applianc Manufacturrs. 28. Dhumidifirs, AHAM DH-1-28, (Rvision of ANSI/AHAM DH [EIA] U.S. Enrgy Information Administration Elctric Powr Monthly. [EIA] U.S. Enrgy Information Administration Frquntly Askd Qustions. [EPA] U.S. Environmntal Protction Agncy ENERGY STAR prsntation. Draft-1_V3._Wbinar.pdf 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-214

12 [EPA] U.S. Environmntal Protction Agncy ENERGY STAR Dhumidifir spcification V3.. ES_Dhumidifirs_Final_V3._Eligibility_Critria.pdf [EPA] U.S. Environmntal Protction Agncy gw_cod=rf [NARA] National Archivs and Rcords Administration. 21. Dpartmnt of Enrgy, 1 CFR 43, Enrgy Consrvation Program for Consumr Products: Tst Procdurs for Rsidntial Dishwashrs, Dhumidifirs, and Convntional Cooking Products (Standby Mod and Off Mod; Proposd Rul. ccp_tp_nopr.pdf Zogg, Robrt and Dborah Albrino Elctricity Consumption by Small End Uss in Rsidntial Buildings, Arthur D. Littl, Inc. Rport to Offic of Building Equipmnt U.S. Dpartmnt of Enrgy. 212 ACEEE Summr Study on Enrgy Efficincy in Buildings 9-215