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RE: [EnergyPlus_Support] Daily Sine wave amplitude....



I guess you could say that for Germany and Austria it more or less flows into legislation in the form of the energy certificates and required processes for building technical systems design. In the case of the second, nothing requires you to design this way, but if you're on the wrong side of a legal dispute everyone will question why you deviate from standard practice. I guess the prevalence outside of "Germania" lies in the fact that good ideas are often copied or incorporated into EU norms. Whether this one is a good idea remains to be seen.

Historically, VDI 2078 has been used for cooling load calculations since the 70's (from memory). And this is the first update since '98. There are a couple of things that are pretty relevant like heat island effects on daily temperature fluxes for cities.

Personally, I don't see it having international appeal in its current form. Unfortunately, I am stuck with it.

 

Hello Jean,

I hadnâ??t heard of VDI 2078 so I did a quick web search. Now I know a little bit about the standard but have more questions.

 

When you have a minute:

How prevalent is the use of VDI 2078 in Germany? Outside of Germany?

Have there been any comparisons done of the predicted loads between VDI 2078 and other typical North American standards/tools (Trace, HAP, etc.)?

 

Should us North Americans become familiar with standard VDI 2078?

 

I am in no hurry for this so donâ??t interrupt your flow!

 

 

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Christopher Jones, P.Eng.
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From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Sunday, April 17, 2016 3:51 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Daily Sine wave amplitude....

 

 

That "is not a sin wave" comment is quite interesting. I've just finished setting up a spreadsheet to create a design day period (CDD) as required by VDI 2078. Since e+ does not yet support a longer warm up period where you can set a different 24 hr schedule for each of the previous 14 days, I am planning on using the caveat in the norm of rerunning the CDD 14 times (but loose the credit inherently given to more massive buildings, which is the point of the CDP). The authors of the norm specify equations based on a sine function, but break it up into 3 parts based on the time of max and min temps.

On 16 Apr 2016 20:26, "Joe Huang YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

I caution that Design Days are by definition atypical conditions with the daily maxima corresponding to either the 0.6% or 1% highest hourly temperatures. Furthermore, the hourly profile described below is extremely generic and applied to all locations and conditions. I don't know how you intend to use the "daily variation sine curve", but if it's to understand the average daily temperatures for each month,  I would recommend calculating the average daily max/min from the weather file or even easier from Wikipedia, and then use the ASHRAE Design Day Profile

to fill out the 24 hour values. If you want to be more location-specific, you can analyze the weather file to derive the average monthly profiles. Last comment is that the daily profiles are not sine curves.

 

Joe

Sent from my iPad


On Apr 16, 2016, at 9:20 AM, Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Dear Heba,

The ASHRAE 2013 Handbook of Fundamentals shows the typical daily temperature range for design days o p 14.11. I doubt that it applies to an entire year, but might be a nice starting point for your work.

Inline image 1

 

On Sat, Apr 16, 2016 at 12:15 PM, hassan_kamel77@xxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Hello,

I am searching for the daily variation sine wave amplitude for a certain city.

I wonder, if it is included in the weather file !!

or, should we make some kind of equations !!

I am simulating a city, where there's high diurnal range between nighttime and daytime.

Thanks in advance,

Heba



 

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