WWR allowances

Hi Julio, 
There are no "limits" on the WWR for any project, but you must be aware that yo uare being measured against a baseline building of the same shape with a WWR of 40% and walls of concrete. In other words, you can have what ever WWR you want but you will have to compensate with a more effecient set of systems and thermal performance of the envelope to reach any energy savings. Platinum or otherwise.

Hi everyone,

I'm gonna chip in here...the WWR is not a prerequisite, but you are competing against the baseline building that does have a good WWR. Modern glazing is pretty good, or better said can be pretty good. U-Values under 0,7 W/m² are not as good a say a wall with insulation at 0,2 W/m², but it is no longer the 1,4 W/m² of the past. The penalty of having glazing area instead of wall still has to be paid.

As for comfort, the analogy is similar. In the coldest of winter in Germany with -14C outside, the inside surface temperature will be at around 18C if the room is normally heated at 21C so the discomfort of radiant asymetry is not that bad. The cold air falling down the surface and flowing across the floor causing draft discomfort also decreases dramatically.

In cold climates this large glazing area makes sence due to passive solar gains setting off heating costs. In hot climates, there is no benifit. But as said before, it can be done at a not so large a penalty as in the past decades.

Bottom line is, it can be done if done correctly, but Im not a fan of glass buildings and in hot climates, I dont see an energy benefite. Running energy models is there to test these things.

Best,

Jean

Hi Julio,

We have worked doing energy modeling on quite a few projects in the Southeast region of the US, and one of the main impacts in the project performance is due to the glass selection, and particularly with the SHGC selection; for these climates you are usually comparing with an 0.25 SHGC for your baseline (in conjunction with the 40% WWR).

So it's doable, but tough, you are going to need to select a really good glazing and also lean on getting more savings from the HVAC and lighting for getting an overall decent energy performance out of your building. As Jean says, I'm also not a fan of glass buildings in hot climates, but that's a lot of what you see around here.

Best,