An aspect of LEED that does not make sense to me

[alps]

I have noticed many large new "green" buildings incorporating LEED design elements are built with large expanses of glass curtain wall ostensibly to maximize natural lighting.

I am no architect but it has always seemed to me that while this might be a sensible approach somewhere warm, in a place like Canada any energy savings on the building lighting side of things would be counteracted by increased costs in building heating. Windows are less insulative than concrete and it takes more energy to heat a building than to light it (I think?). It seems to me that a truly green building in a cold climate would have zero windows and a lot of insulation, as an extreme example.

I am sure I am overlooking something but would someone help me out . Here's the type of thing I'm talking about:

Nova Scotia Community College, Waterfront Campus


(eaglewood dj @ flickr)

2011 Canada Games Centre rendering


(Halifax Regional Municipality)

Citadel High School

(Wikipedia)

[trueviking]

'green' buildings are trying to achieve much more than energy efficiency....they are trying to create healthy environments....in LEED, something like 12 of 80 points are devoted to building energy use.

if you look through the categories of LEED you will see that it stresses the reduction of embodied energy....local materials that use less energy to transport, recycled materials, as well, reduced water use, low VOC's.....there is a large scope of issues that a sustainable building is responding to.

as for the windows....part of creating a good internal environment is access to daylight and views....you are probably right that if energy efficiency was your only goal a windowless box with lots of insulation would be best, but that would not be a healthy environment.

there is a definite balance that has to be found to improve the insulative value in glass buildings...tripple pane glazing and double wall glazing technology has come a long way, but it is still much less efficient than a solid wall.....often glass walls are actually made up of solid spandrel panels that look like glass but actually have high insulatoin behind them.

a south facing glass wall that is properly sun shaded can be effective even if its R-values are lower...there is heat gain in the winter from the low sun...this has to be shaded in the summer to avoid high cooling costs....an effective solar control strategy can make a glass wall quite effective and efficient....i have no idea how those buildings that you posted are getting away without any solar shading.....

there is also the issue of lighting...by having large amounts of daylighting some of the energy loss is recouperated by a reduction in artificial lighting use.

[slide_rule]

even in the cold, there is still solar gain.

on the other hand, hot climates generally wouldn't want solar gain, but (in hot, humid climes) they'd want ventilation.

[someone123]

Originally Posted by trueviking

i have no idea how those buildings that you posted are getting away without any solar shading.....

They're in Halifax - there is no sun.

[alps]

Originally Posted by trueviking

'green' buildings are trying to achieve much more than energy efficiency....they are trying to create healthy environments....in LEED, something like 12 of 80 points are devoted to building energy use.

if you look through the categories of LEED you will see that it stresses the reduction of embodied energy....local materials that use less energy to transport, recycled materials, as well, reduced water use, low VOC's.....there is a large scope of issues that a sustainable building is responding to.

as for the windows....part of creating a good internal environment is access to daylight and views....you are probably right that if energy efficiency was your only goal a windowless box with lots of insulation would be best, but that would not be a healthy environment.

there is a definite balance that has to be found to improve the insulative value in glass buildings...tripple pane glazing and double wall glazing technology has come a long way, but it is still much less efficient than a solid wall.....often glass walls are actually made up of solid spandrel panels that look like glass but actually have high insulatoin behind them.

a south facing glass wall that is properly sun shaded can be effective even if its R-values are lower...there is heat gain in the winter from the low sun...this has to be shaded in the summer to avoid high cooling costs....an effective solar control strategy can make a glass wall quite effective and efficient....i have no idea how those buildings that you posted are getting away without any solar shading.....

there is also the issue of lighting...by having large amounts of daylighting some of the energy loss is recouperated by a reduction in artificial lighting use.

Great post, thanks for the info. I still think it's odd that any building with that much glass would be considered a "leader" in green building design. Seems more about style over substance if LEED is supposed to be about sustainability.

[aic4ever]

Originally Posted by alps

Great post, thanks for the info. I still think it's odd that any building with that much glass would be considered a "leader" in green building design. Seems more about style over substance if LEED is supposed to be about sustainability.

You presuppose that engineers are unaware of how to figure out passive ways of dealing with this. Here is a great article on the recent library at Loyola University in Chicago, dead on Lake Michigan, and how they handled the extreme weather conditions with such an expanse of glass.

http://www.bdcnetwork.com/article/37...tification.php

http://www.bdcnetwork.com/article/37..._Enclosure.php