Revision history [back]

I am struggling to correctly model a laboratory ventilation system with multiple vav fume hoods in Openstudio. I have 8 hoods with vav sashes and I've made a schedule similar to a lighting schedule that I want to apply to the peak fine exhaust rate to simulate a variable number of open hood sashes through a typical day. I am using a vav air handler with dx cooling coil and hot water heating coil in the ahu and hw reheat coils for the lab zones. Each lab contains 8 hoods and each hood has a maximum of 1200 cfm of exhaust. I am using a manifolded exhaust system rather than one exhaust fan per hood. I am constraining my exhaust system to a maximum flow of 19200 cfm and a minimum flow of 15000 cfm so that I keep a minimum exhaust stack velocity (so not a large degree of exhaust fan energy savings from vav hoods, but I will save a lot on makeup air conditioning). I placed a variable speed exhaust fan on the exhaust node at the air handling unit. Do I hard size the exhaust fan min and max cfm and apply the fine hood schedule? Do I apply the same hard settings and/or schedule to my supply fan? Also because I have no return duct I turned off economizer in the ventilation control object for the ahu. I also noticed that there are some zone flowrate control options for each of my lab zones but I don't know whether to use those or the fan flow controls.

I am struggling to correctly model a laboratory ventilation system with multiple vav fume hoods in Openstudio. I have 8 hoods with vav sashes and I've made a schedule similar to a lighting schedule that I want to apply to the peak fine fume exhaust rate to simulate a variable number of open hood sashes through a typical day. I am using a vav air handler with dx cooling coil and hot water heating coil in the ahu and hw reheat coils for the lab zones. Each lab contains 8 hoods and each hood has a maximum of 1200 cfm of exhaust. I am using a manifolded exhaust system rather than one exhaust fan per hood. I am constraining my exhaust system to a maximum flow of 19200 cfm and a minimum flow of 15000 cfm so that I keep a minimum exhaust stack velocity (so not a large degree of exhaust fan energy savings from vav hoods, but I will save a lot on makeup air conditioning). I placed a variable speed exhaust fan on the exhaust node at the air handling unit. Do I hard size the exhaust fan min and max cfm and apply the fine hood schedule? Do I apply the same hard settings and/or schedule to my supply fan? Also because I have no return duct I turned off economizer in the ventilation control object for the ahu. I also noticed that there are some zone flowrate control options for each of my lab zones but I don't know whether to use those or the fan flow controls.

I am struggling to correctly model a laboratory ventilation system with multiple vav fume hoods in Openstudio. I have 8 hoods with vav sashes and I've made a schedule similar to a lighting schedule that I want to apply to the peak fume exhaust rate to simulate a variable number of open hood sashes through a typical day. I am using a vav air handler with dx cooling coil and hot water heating coil in the ahu and hw reheat coils for the lab zones. Each lab contains 8 hoods and each hood has a maximum of 1200 cfm of exhaust. I am using a manifolded exhaust system rather than one exhaust fan per hood. I am constraining my exhaust system to a maximum flow of 19200 cfm and a minimum flow of 15000 cfm so that I keep a minimum exhaust stack velocity (so not a large degree of exhaust fan energy savings from vav hoods, but I will save a lot on makeup air conditioning). I placed a variable speed exhaust fan on the exhaust node at the air handling unit. Do I hard size the exhaust fan min and max cfm and apply the fine fume hood schedule? Do I apply the same hard cfm settings and/or schedule to my supply fan? Also because I have no return duct I turned off economizer in the ventilation control object for the ahu. I also noticed that there are some zone flowrate control options for each of my lab zones but I don't know whether to use those or the fan flow controls.controls or both.

I am struggling to correctly model a laboratory ventilation system with multiple vav VAV fume hoods in Openstudio. Openstudio.

I have 8 hoods with vav sashes and I've made a schedule similar to a lighting schedule that I want to apply to the peak fume exhaust rate to simulate a variable number of open hood sashes through a typical day. I am using a vav VAV air handler with dx DX cooling coil and hot water heating coil in the ahu and hw AHU and HW reheat coils for the lab zones.

Each lab contains 8 hoods and each hood has a maximum of 1200 cfm of exhaust. I am using a manifolded exhaust system rather than one exhaust fan per hood. I am constraining my exhaust system to a maximum flow of 19200 cfm and a minimum flow of 15000 cfm so that I keep a minimum exhaust stack velocity (so not a large degree of exhaust fan energy savings from vav hoods, VAVh oods, but I will save a lot on makeup air conditioning). I placed a variable speed exhaust fan on the exhaust node at the air handling unit.

Do I hard size the exhaust fan min and max cfm and apply the fume hood schedule?

Do I apply the same hard cfm settings and/or schedule to my supply fan?

Also because I have no return duct I turned off economizer in the ventilation control object for the ahu. I also noticed that there are some zone flowrate control options for each of my lab zones but I don't know whether to use those or the fan flow controls or both.