Energy saving performance and economic anaIysisofexhaustairenergy recovery ofan unheated underground garage in Beijing

Aiming attheproblem ofwhethertheexhaustairenergyrecovery from unheatedunderground garagesincoldzoneisenergysaving andeconomical,theairtemperatureandhumiditybothinsideandoutside ofanunheatedundergroundgarage in Beijing are testedfor4 years.Based on the measureddata,the energy saving performanceand economicimpactofexhaustair sensible heatrecovery ofthe underground garage are quantitatively analysed.Theinfluenceofdifferentseasons,exhaustpositionsandoperationmodesisanalysed. Theeffectoffrostin winter is also taken into account.The results show thatin the intermittent operation modeofofficebuildings,the average energy saving ofthe exhaust air sensible heatrecovery device is0 . 125 kw ·h/(m3 /h)during the air conditioning season,0 . 547 kw · h/(m3 /h)during the heating season,and 0 . 672 kw · h/( m3 /h)throughout the year.The average ratio of energy recovery is 9 . 1 during the air conditioning season,and16 . 2 during theheating season.The average investmentpaybackperiodis5 . 9 years for the intermittent operation mode and 2 . 0 years for the continuous operation mode. Therefore, the application oftheexhaustairsensible heatrecovery device to unheated undergroundgaragesin cold zone can producesignificantenergysaving and economicbenefits.