[Bldg-sim] eQuest - Energy consumption increasing on reducing Glass U-Value

akshay gupta akshaykg at gmail.com
Fri Nov 3 06:18:52 PDT 2017


Hi Jim

Thanks for the reply. Actually, the project we are modelling are designed
to be energy efficient commercial spaces. So for example, interior LPD is
not more than 0.5 W/sqft (LED lights), EPD is around 2.0 - 2.5 W/sqft,
Occupant Density is around 50 Sqft /person. So I dont see any area where
internal heat gain is unusually higher where the building needs to cool
itself off by conducting heat outside (inside hotter than outside).

I think there something else.

Regards

Akshay

On 3 November 2017 at 18:42, Jim Dirkes <jim at buildingperformanceteam.com>
wrote:

> Akshay,
> While there are many things that could contribute to this situation,
> consider:
> A smaller U value means that there is *less *conduction through the
> construction. With less conduction, a smaller cooling load will normally
> decrease cooling energy.
>
> An exception to this is when internal loads are higher than normal. In
> that case, the building needs to get rid of internal heat (provide cooling)
> most of the year. When the envelope has more insulation (lower U-value), it
> inhibits heat removal and can increase cooling energy.
>
> Thanks to my friend Javed Iqbal for reminding me of this recently. He is
> preparing a paper which discusses this phenomenon for buildings in the
> central European climate.
>
> On Fri, Nov 3, 2017 at 8:37 AM, akshay gupta via Bldg-sim <
> bldg-sim at lists.onebuilding.org> wrote:
>
>> Hi There
>>
>> I am facing an issue in eQuest in almost all simulation models for most
>> hot and composite indian climates. Whenever we reduce U-value of glass in
>> model, from Single Glazing U-Value of 1 Btu/hr Sqft F to 0.32 Btu/hr Sqft F
>> (or any other U-value lower than 1), we see an increase in energy
>> consumption.
>>
>> Can someone point out principal mistake that may be making in the model.
>>
>> Thanks in advance.
>>
>> Regards
>>
>> Akshay Gupta
>>
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>
>
> --
>
> James V Dirkes II, CEO / President
> The Building Performance Team Inc.
> 1631 Acacia Dr, Grand Rapids, MI 49504
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