[Equest-users] No impact when changing U-values

Pasha Korber-Gonzalez pasha.pkconsulting at gmail.com
Tue Jan 18 12:12:20 PST 2011


Hi Omar,

this is where the building "science" comes into play.  If you are not seeing
a noticable difference on your building energy when you change your envelope
loads, then this is because your building loads are not driven by the
envelope loads (i.e. wall thermal losses, window thermal losses/gains, etc.)

So, I ran your model and also found that a change in Wall insulation makes a
very small difference in energy use.  Therefore it prodded me to dig further
inot your building loads to see what was driving the loading on the
building...A look at the LS-C report (attached) gives us a nice picture...


   - For your cooling loads-
   - your wall conduction only makes up 3% of your total cooling load
   - your window conduction/solar makes up only 14% of your total cooling
   load
   - your occupants make up 24% of your cooling load
   - your lights make up 15% of your cooling load
   - and then you have a large load attributed to your ground floor surface
   conduction and equipment to space loads

With such a large occupant load, I'm also guessing that your ventilation
load (OA per person) is a HUGE driving factor for your building loads too.

Based on this info I can conclude to tell you that "you are barking up the
wrong tree" with evaluating ECM's for your envelope performance.  Any money
or efforts put toward a better envelope will yield little, to no savings &
payback for your design efforts.

The great thing about simulation is that it gives us a "picture" of the
whole building science of our projects so that we can disect them and
understand what is making them "run" so-to-speak and then identify the best
ways to improve them based on how they "run."

Hope this helps,

Pasha

Korber Energy Consultants



On Tue, Jan 18, 2011 at 5:10 AM, Omar Katanani <omar at ecoconsulting.net>wrote:

>  Dear all,
>
>
>
> It’s been a while!
>
>
>
> I’m having some trouble with my simulations..
>
>
>
> I just realized that, for the files attached, increasing the U-values of
> the windows & walls dramatically (x10 times) is not increasing my
> consumption results, but even decreasing the consumption of some categories!
>
>
>
> This is counter-intuitive, as increasing the U-values should mean that the
> building is gaining/losing more heat to the external environment, and would
> thus mean that more energy is required to condition the space!
>
>
>
> I have been changing the U-values of:
>
>
>
> Ø       EL1, EL2, EL3, EL4, EL5, and EL6 EWall Construction
>
> Ø       All the Windows
>
>
>
> Can someone please have a look at the files attached and advise
> accordingly?
>
>
>
> Many thanks,
>
> Omar
>
> ___________________________
>
> Omar Katanani
> Sustainable Design Engineer
>
> Email: omar at ecoconsulting.net
>
>
>
> EcoConsulting (Lebanon)
>
> Nahas Building, 4th floor
>
> 4 St-Maron Street / Georges Haddad Avenue
>
> Postal Code: 2028 5806 SAIFI
>
> Beirut, Lebanon
>
> Tel:          +961 (0) 1 971 266
> Mobile:    +961 (0) 3 045 045
>
>
>
> EcoConsulting (UK) Ltd
> 28 Marshalsea Road
> London, SE1 1HF
> Tel:  +44 (0) 207 939 0989
> Fax:  +44 (0) 207 939 0981
>
> Website: www.ecoconsulting.net
>
>
>
>
>
>
>
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