Re: [TRNSYS-users] Hot periods data

[David Bradley <bradley@tess-inc.com>]

Benoît,
  Some years ago, there was an ASHRAE research project to look into this because it is not quite sufficient to add an offset and because you need design day combination of solar, temperature, and humidity. The result was a software tooled called "Extremes." I am not sure whether the software is still available or not but its intent was to generate extreme sequences of hot or cold conditions based on historical weather data.

Kind regards,
 David


B.Cogné - dH Technologies wrote:

Dear Trnsys users,

 

I am simulating an office building in order to evaluate the summer comfort without air conditionning.

My idea is to base this analysis on the periods during wich a reference indoor temperature (lets say 25°C) is exceeded, each period being defined by its duration and the maximum amplitude of the temperature exceeding, and then calculate the quantity of periods per month, or year, for couples of durations and exceedings ranges.

The problem I am facing is the definition of the meteorological data.

The TMY2 file in Trnsys for the site I am studying is Lorient - France.

I appears that this file does not include one day with the extreme annual design dry bulb we can find in Ashrae tables for design conditions, neither a day with the 0,4% Monthly design dry bulb temperature.

Example for the period of july and august:

- maximum design dry bulb in TMY2 file: 27,4°C

- Ashrae extreme annual design dry bulb - Mean : 31.2°C

- Ashrae Monthly design dry bulb 0.4% - July : 30.9°C

- Ashrae Monthly design dry bulb 1% - July : 29.1°C

- Ashrae Monthly design dry bulb 0.4% - August : 30°C

We see that these 4 extremes values are very far from the maximum found in TMY2.

Even it is clearly stated in TMY2 documentation that the data are built for energy analysis only, and not for sizing purposes, it is surprising to see such differences, as "dynamic" comfort analysis is also very important.

I am therefore looking for some advice on the way to proceed.

I am ready to make some tricky adjustments by adding an offset on the extreme temperatures of the TMY2 data in order to reach the annual extreme (Mean) but I don't know if it makes sense.

 

Looking forward for your help,

 

Best regards

 

Benoît Cogné

DH TECHNOLOGIES

France

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