Guest guest Posted December 31, 2009 Report Share Posted December 31, 2009 Hi , If the conference room HVAC was appropriately designed, then thermal comfort and appropriate ventilation rates should be achievable without fully opening the VAV. If the design temperature in the room is achieved, then the VAV box will and should back-off. Also the VAV may also be set-up so that it does not fully open under any circumstances (except possibly smoke purge). Many design deficiencies are associated with the tenancy fitout designs. Remember that more than likely the base building was designed (in the 1980’s~mid 2000 era) for open plan, unpartitioned space and then the occupant was supposed to engage a competent designer to ensure that the HVAC was amended to reflect their specific occupancy. Cost constraints usually meant that this was achieved using the base building HVAC and we know just how ineffective that this is for conference rooms etc and especially where base building VAV systems are used. I recently reviewed a system where the conference room was supplied by four (4) VAV’s with the controlling thermostats all grouped together adjacent to the entry door. The VAV’s were constantly hunting for setpoint and this was further compromised by the customer installing slab-to-slab partitioning (for acoustic seal and for security) which was obstructing the return air through the ceiling plenum. Conference rooms are by their very nature a transient load with variant occupation numbers and to achieve thermal comfort as well as adequate diffusion rates requires a quite sophisticated design. I would always lean toward something with a broad range of capacity control for the room and would base it at not less than the maximum expected occupation within any 30-minute period (usually seating capacity +10% at 300W/seat + fabric load) and diffusion ventilation capacity rates of not less than 10L/s/person of Outside Air where high grade filtration is used increasing to 30L/s/person for medium grade filtration. Temperature Control should be by thermostat while OA ventilation supply to the room should be by CO2 sensing. Unless VAV’s are exclusively responding to fabric/solar loads, they should be controlled by a single zone thermostat. Return air capacity from the room should be verified. Regards, Engineering & Compliance Support for Building Services  Ian Childs New Directions International Business Services Pty Limited ABN.49.083.184.751 PO Box 26 Oatley NSW 2223 Australia ian@... www.ndibs.com.au www.safeworkmethod.com.au www.oatleyweather.com.au MSN: childsian@... YM: newdirectionsint ICQ: 85002610 AIM: ianatndibs telephone: fax Sydney: fax Melbourne: fax Brisbane: mobile: VoIP Skype ID: VoIP softphone: +61(0)2 9594 4477 +61(0)2 8090 1026 +61(0)2 8569 1015 +61(0)3 8080 1795 +61(0)7 3319 8999 +61(0)414 472 042 childsian 09141426mynetfone.au Building Services Engineering & Facility Maintenance Management Advisory, Fire Safety Reports & Statements, OH & S, Forensic Engineering, IR‑Thermography, Energy Audits, Environmental Audits, Building Code Assessments, Disability Access, Risk Evaluation, Material Hazard, Water‑Quality, Air Quality, Thermal Comfort & Close Control A/C, Smoke Control, Equipment condition assessments Add me to your address book... more info? DISCLAIMER AND TERMS GOVERNING ELECTRONIC COMMUNICATIONS This e-mail (including any attachments) is confidential and may be protected by legal professional privilege. If you are not the intended recipient of this e-mail you are advised that any use, reproduction, disclosure or distribution of the information contained in the e-mail is prohibited. If you have received this e-mail in error please reply to us immediately and delete the e-mail. While an up to date anti-virus software is being used by us, no warranty is made that this e-mail is free from computer virus or other defect. Any loss/damage incurred by using this e-mail is not the sender’s responsibility. Please consider not printing this email unless absolutely necessary __________ Information from ESET NOD32 Antivirus, version of virus signature database 4733 (20091231) __________The message was checked by ESET NOD32 Antivirus.http://www.eset.com Quote Link to comment Share on other sites More sharing options...
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