Adding blinds in SBEM

shelley · Posts: 3

Hi,

Can you advise how to add blinds to the window construction details?

The help topic suggests that in order to be able to add shading you need to use layers to define the window construction but this doesn't appear as an option in the drop down menu.

Any help much appreciated...

Andrew Bairstow · Site Admin Posts: 343 Location: Birmingham, UK

The SBEM model for window shading only considers (external) shading of overhangs and fins. For external blinds then you can use the options 'external solar proptection...' or treat each louvre as an overhang shading the window in between each pane. SBEM does not really provide a model for inter-pane or internal blinds though there are calculation methods for these which could be applied if you were confident to use them. Any method would still come down to simply providing a shading transmission factor (or modifying the g value referred to as 'T solar'). I would start with investigating the likely effect of modelling the shading by setting different transmission factors: eg compare 0.5 with base 1.0. You may find it makes very little difference or too little for it to be worthwhile investigating further.
If you wish to pursue it further then CIBSE TM37 provides a method for recalculating the g value of glazing with different types of blind.
Regards
Andrew

Phildodd · Posts: 30

Blinds dont help a great deal to control solar gain unless they are reflective, installed outside or between the panes. Once the solar radiation hits the blind inside the space, it heats the blind and acts as a again in the room and I think this is why SBEM does not consider internal blinds. The only great benefit to blinds is that they cut down the immediate effect of solar radiation, the sudden increase in heat you feel when the sun comes out from behind a cloud.
Blinds that reflect the solar rediation back out of the space can be effective and can be estimated by using a modified G factor for the glazing.
Hope this is clear and helps a little.

johnmcc · Posts: 12

Surely now this can be done for the purposes of the new building regs part L 2010. The BRUKL output lists rooms with a large amount of solar gain (passive) and lists if they have blinds. How do I sat it has blinds and reduce the solar gain??

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