Hello All,
We are now preparing the Energy modelling for one of our projects located outside USA. It is a 2 storey non-residential building with VRV system for cooling only.
We would like to get your advice on defining the baseline HVAC system. From ASHRAE 90.1-2007, Appendix G, table G3.1.1A, the HVAC system PSZ-HP should be used as our baseline since our building does not have the heating system. However, we have the following issues:
1. We are not sure if we need to use the same part load ratio as our design case in our baseline HVAC system (but I think this is not correct since we are using VRV system which is different from DX/heat pump).
2. If we can use the different part load curve, we would like to know which part load curve we should use for our baseline HVAC system.
Any advice would be greatly appreciated. Many thanks.
Cheers,
Grace
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 11, 2012 - 9:36 am
What software are you using? Many of them cannot model VRV systems directly and must use a work around.
You are correct that the VRV and heat pumps are different.
Grace Ming
Senior ESD Consultant95 thumbs up
June 11, 2012 - 8:00 pm
Thanks Marcus for your reply.
We are using IES VE software. Since it can't model VRV system directly yet, we will manually set up VRV efficiency in ApacheHVAC module. Any advice on the baseline heatpump properties? Many thanks.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 11, 2012 - 10:32 pm
I don't know enough about IES-VE to say. Can it model regular heat pumps?!? If it can't then I would be very suspect of any work around for VRV systems.
Grace Ming
Senior ESD Consultant95 thumbs up
June 13, 2012 - 6:59 am
Hi Marcus,
Yes, IES-VE can model the regular heat pumps. We are not sure which part load efficiency to be used in the baseline model.
For our case, from ASHRAE 90.1-2007 Table 6.8.1B, we have to use the min efficiency for air cooled (cooling mode) > 240,000 Btu/h is 9.5EER (as of 1/1/2010) with 9.2 IPLV in our baseline model. Since IPLV = 1/ ((0.01/A)+(0.42/B)+(0.45/C)+(0.12/D)) where A = EER at 100% , B=EER@75%, C=EER@50% and D=EER@25%.
How can we determine the EER for 100%, 75%, 50% & 25% based on the ASHRAE 90.1 min requirements of 9.2 IPLV & 9.5 EER for the baseline model? Or which part load efficiency we should use in our baseline.
Many thanks,
Grace
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 13, 2012 - 10:05 am
We enter the 90.1 efficiency. The software contains a default curve that we use so no need to determine part-load efficiency.
The part-load curve should be in accordance with the test procedure standard in Table 6.8.1B. In this case ARI 340/360 which I think is available for free.