Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Heating and cooling sizing factor in energyplus

asked 2015-01-08 05:04:04 -0600

Xandrika's avatar

updated 2020-03-10 09:54:18 -0600

As I understood, heating and cooling sizing factor are applied to all kind of simulation using the AHRAE standard values of 1.25 and 1.15, respectively. But when we try to design energy-efficient buildings, we should avoid oversizing of equipment?

I would like to discuss with you this topic. Please, feel free to add your opinion and describe your cases when and for what you use the heating and cooling sizing factors in energyplys. Thanks.

edit retag flag offensive close merge delete



Are you referring to the following object in EnergyPlus?

1.25,                     !- Heating Sizing Factor
1.15,                     !- Cooling Sizing Factor
;                        !- Timesteps in Averaging Window
Alex Vlachokostas's avatar Alex Vlachokostas  ( 2022-04-04 13:58:40 -0600 )edit

1 Answer

Sort by ยป oldest newest most voted

answered 2015-01-08 05:21:31 -0600

We should certainly avoid oversizing equipment, both for the sake of cost and for embodied energy/material efficiency reasons.

However the oversizing is required since the weather files we use don't represent the harshest winters/hottest summers. It's reasonable to expect extreme weather events, especially given expected climate change. Without oversized plant there is a risk that the occupants will be left uncomfortable, and that should be one of the prime drivers when designing a system.

edit flag offensive delete link more


Hey Jamie, According to Ashrae, I understand that heating size 125% and cooling size 115% But for Proposed building, need we oversize the cooling/heating too?


Jenny Gao's avatar Jenny Gao  ( 2015-01-20 16:37:43 -0600 )edit

I don't know (I'm UK-based) but I would assume so.

Jamie Bull's avatar Jamie Bull  ( 2015-01-21 03:38:05 -0600 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools

1 follower


Asked: 2015-01-08 05:04:04 -0600

Seen: 1,284 times

Last updated: Jan 08 '15