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What's it for?
The pages DJU allow you to analyze climatic variations using Unified Degree-Days (DJU). These indicators measure the difference between outside temperatures and a reference temperature, to better assess heating (winter) or cooling (summer) requirements. This helps to understand the impact of climatic conditions on building energy consumption.
Prerequisites
In order to view this page, you must be an Eficia customer and request activation of this page from your Eficia project manager.
How do I access it?
Monitoring Park > Indoor air > DJU
Monitoring Site > Indoor air > DJU
How does it work?
Winter DJU
Measures heating requirements.
Summer DJU
Measures cooling requirements.
Total DJU
Sum of winter and summer DJUs. It measures the need for thermal regulation.
How are DJUs calculated?
The DJU is calculated on a daily basis. It corresponds to the difference between the average temperature of the day and the reference temperature, which is defined at 18°C. This reference temperature is used for both summer and winter UDDs.
To obtain the UDD for the month visible in the park view, the daily UDDs are added together.
Calculation method
- Tn: minimum temperature of day D recorded between D-1 (the day before) at 6pm and D at 6pm UTC.
- Tx: maximum temperature of day D recorded between D at 6am and D+1 (the day after) at 6am UTC.
- S: selected reference temperature threshold. (18)
- Moy = (Tn + Tx ) /2 : Average temperature of the day
DJU hiver
- If S > TX : DJ = S - Moy
- Si S ≤ TN : DJ = 0
- If TN < S ≤ TX : DJ = ( S - TN ) * (0.08 + 0. < 42 * ( S -TN ) / ( TX - TN ))
DJU Ete
- Si S > TX : DJ = 0
- Si S ≤ TN : DJ = Moy - S
- Si TN ≤ TX : DJ = ( TX - S ) * ( 0.08 + 0.42 * ( TX - S ) / ( TX - TN ))
Frequently asked questions
Where do the weather data come from?
Eficia's weather data comes fromOpenweather.
Why are the summer UDDs zero?
Summer UDDs are often zero during the winter months, as temperatures generally do not exceed the air-conditioning threshold.
How are UDDs interpreted?
A high winter UDD means that outside temperatures are well below the reference temperature, indicating an increased need for heating. A summer UDD indicates a need for air-conditioning.
Can UDDs be compared between sites?
Yes, the park view table enables direct comparison of UDDs between different sites for a given period.