I agree with Vaibhav. Long ago, 25-30 years or so, I believe Larry Spielvogel wrote an ASHRAE Journal article about this. The concept was called ?optimum U value? (or something similar).
The impact of using more or less insulation varies with climate and internal loads, but it?s somewhat counter-intuitive; more insulation is not always better!
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
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From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Vaibhav Jain
Sent: Saturday, September 08, 2012 10:01 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Increased insulation run
Hi,
It might be because - when you have more insulation the heat from internal gains is trapped inside (due to high insulation) even during night time when outside is cooler. The opposite should be in case of low insulation. Thats why high insulation is not always/everywhere good, it could bring penalty too.
Vaibhav Jain
On 7 September 2012 22:31, cmcdona037 <mcdonald.cliff@xxxxxxxxx> wrote:
Hello,
I am doing a parametric run for a building with increased insulation. For some reason, increasing the insulation results in a fairly significant increase in building fan energy. However, when you look at the sizing, the baseline case has slightly larger fans than the efficient case, as expected. If you look at the occupant comfort report, most spaces are slightly cooler in the summer and warmer in the winter in the efficient case, so I guess this is the reason behind the higher energy use. But why is this happening? Is there a setting I can use to get the same level of heating/cooling in both cases?
--Niraj Poudel, Architectural Engineer.PhD student, PDBE Program.Clemson University, Clemson, SC.
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