[Bldg-sim] Perimeter Slab Insulation

[JRR]

John Ross wrote;

    Remember the climate is usually dryer in Winter reducing the ground 
thermal coupling for most
    climates. This would probably be reversed for California and South 
Texas / Houston areas.

David Bradley wrote:
> Keith,
>  If you have a cooling dominated application and a relatively cool 
> average annual ground temperature, insulating underneath the slab is 
> going to disrupt some amount of free cooling that you are getting. 
> Adding insulation would drive cooling energy up a bit and heating 
> energy down. Depending on the magnitude of the heating and cooling 
> changes, you could see a net increase in HVAC energy over the year. An 
> increase in heating energy and no change in cooling energy is a bit 
> suspicious. You might look into how the software you are using models 
> the ground heat transfer. There has been a good bit of work done and 
> recently wrapped up under IEA Task 34/45 on evaluating the ground 
> coupling models used by various simulation tools.
> Kind regards,
>  David
>
>
> Keith Swartz wrote:
>>
>> Do any of you know the reasoning behind why the 2006 edition of the 
>> International Energy Conservation Code (IECC) removed the requirement 
>> for insulation for unheated slabs for some climate zones? I have done 
>> a few energy models recently with slab insulation as a potential 
>> energy saving measure. The numbers were very small, which was 
>> expected, but what surprised me was that the savings were negative. 
>> Adding insulation to the slab actually _increased_ annual energy 
>> usage (very slightly). Cooling was unaffected, but fan energy was 
>> slightly higher during the heating season. My quick search for 
>> research reports or other insights to explain this came up empty. Do 
>> any of you have any thoughts? Are the results so insignificant that 
>> the differences I am seeing in the calculations could just be 
>> considered "noise"?
>>
>>  
>>
>> _____________________
>>
>> Keith Swartz, P.E., LEED AP
>> Energy Engineer / Senior Project Manager
>> Energy Center of Wisconsin
>> 455 Science Drive, Suite 200
>> Madison, WI 53711
>> Phone: 608.238.8276 x123
>> Fax: 608.238.0523
>> Email: kswartz at ecw.org <mailto:kswartz at ecw.org>
>> Web: www.ecw.org <http://www.ecw.org>
>>
>> *Energy Center University
>> */Your gateway to sustainable design training and online education 
>> programs.
>> /www.ecw.org/university/ <http://www.ecw.org/university/>
>>
>>  
>>
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>>
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>
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