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Re: [EnergyPlus_Support] Re: winter design day
Thanks for the quick reply, but to be honest I'm still not convinced. If a
design day is intended to be worst case scenario (as opposed to realistic
weather simulation) then why wouldn't summer design days also have a 0 daily
temperature range?
You seem to be saying that there is an unspoken assumption in HVAC that heat
is always on in the winter, but cooling is only when you actually need it in
the summer. Is it the experience of building designers that once you get
below a certain outside temperature then a few degrees either way makes no
difference in heating loads?
----- Original Message -----
From: "JV Dirkes II" <jvd2pe@xxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Wednesday, June 24, 2009 10:44 AM
Subject: [EnergyPlus_Support] Re: winter design day
> Jerry,
>
> Without checking E+ docs, but using my experience......
> A "design day" is a "worst case" condition. For winter, that means a
> sustained cold period with no sun and no internal heat (e.g., lights or
> PCs). Using a zero degree daily range is a fairly normal approach to
> those criteria.
> A practical example in Michigan, where I'm from, would be an extended
> weekend (say, Christmas) when the temps drop very low and stay there for
> hours on end. The sun, as is usual in MI, doesn't shine. (Of course it
> could also be night time. We're why light therapy got popular.
> In that instance, the heating system is all you've got; it better be big
> enough!
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jerry McManus" <jerrymcm@...>
> wrote:
>>
>> Hi Folks,
>>
>> I'm new to EnergyPlus, and a total noob when it comes to HVAC, so please
>> be gentle! Here's my first newbie question:
>>
>> While learning about design days I was confused by the fact that all of
>> the winter design days in the example weather data have a 0 daily
>> temperature range modifier. Searching the input\output reference yielded
>> this note:
>>
>> "Note that usual Winter design conditions are for very cloudy days
>> (clearness = 0), and low temperatures (temperature range=0)."
>>
>> Unfortunately no explanation is given why low temperatures should have 0
>> for the daily temperature range...? This is one of those things that is
>> probably obvious to an HVAC pro, but it's not at all clear to me why a
>> winter design day should not bother with highs and lows in the
>> temperature range.
>>
>> Any help will be greatly appreciated. Thanks!
>>
>
>
>
>
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