Hi everyone - I am trying to gauge the impact of a change in exterior wall insulation on the cooling demand of a building model. I am using HB Color Rooms to visualize the ‘cooling’ output from HB Read Room Energy Result.
The model seems to be working fine (I always get numerous errors in the HB Model to OSM component, but nothing Severe) and when I do things like change the window extrusion depth, or change the window SHGC, I get predictable changes in the CEI. It’s the solid surfaces that seem to make no difference. Here are some visuals from the model. The sum of all CEI results for each room stays at ~418 regardless of any insulation changes. Logically, I would think that CEI would decrease with improved envelope insulation.
Any idea what could be going wrong? Or maybe is this working and I’m not seeing some other limitation in the way the Ideal Air loads are being calculated?
I frustratingly can only upload one image so this is proof at least that the R-value is being read properly.
Hi @bmpietras,
It depends on the climate, space usage, and the range of r-values you’re testing. But for UK and Middle East climates I’m familiar with modelling I would expect cooling energy to mostly driven by solar and internal gains. U/R value is going to have pretty minimal impact on cooling within building code requirements.
The delta T between indoor and outdoor in cooling periods is typically relatively small and so changes to insulation will have limited impact.
Cheers,
Charlie
1 Like
Hey Charlie - thanks for the feedback! This project is in NYC so not too far off from the UK. The building (one of many on a campus) was constructed in 1962 and has no insulation at all currently. We’re trying - at a schematic level - to assess what the most cost effective method of reducing cooling demand (replace windows, overcladding, shading devices) since peak loads are double the winter heating demand.
That’s an interesting insight - we’ve worked on a few PHI/PHIUS new builds where a highly insulated envelope is a given so we applied the same logic here, but perhaps with the mass wall you’re on to something. Especially with a retrofit. Internal heat gains should be considered fixed (apartment building). When I ran a model emulating triple-glazed PHI windows the impact on cooling was dramatic which supports your conclusion.
1 Like
