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Degree days as divisor with area-based weighting

Reports support using degree days (HDD/CDD) as a divisor to calculate specific consumption.
To ensure fair comparison between entities, a weighting factor is applied, which can be:

  • building area (IA = Individual Area)
  • aggregated area (AA = Aggregated Area, e.g. GFA)

This logic is equivalent to weighting based on object properties.

How It Works​

When using degree days as a divisor:

  • The system does not simply calculate consumption / HDD or CDD
  • HDD or CDD are weighted based on the area of each entity
  • A weighted average of degree days is calculated
  • The total consumption is divided by this weighted value

Template Configuration​

To generate the report, the template must be configured correctly:

  1. Select the desired energy (e.g. gas)
  2. Enable “Add degree days divisor”
  3. Select the degree day type:
    • Cooling degree days (CDD)
    • Heating degree days (HDD)
  4. Choose the weighting factor (e.g. GFA)

Template

Specific Consumption Calculation for Multiple Entities​

If the report includes multiple entities (portfolio, site, group of buildings),
you cannot just sum or average HDD – different-sized entities affect consumption differently.

Therefore, the system uses area-based weighting:

  • Each entity contributes proportionally to its area
  • Larger entities have greater influence on the result
  • Area does not appear in the final unit – it serves only as a weight

For a single entity, the calculation is simple:
consumption / HDD

For multiple entities:

Specific consumption = total consumption / weighted HDD (by area)

Calculation Principle​

  1. Calculate the weighted average HDD based on areas
  2. Sum the total consumption of all entities
  3. Divide total consumption by the weighted HDD

Example – Step by Step​

We have two buildings:

Building A

  • Consumption: 500 m³
  • Area: 10 m²
  • HDD: 41

Building B

  • Consumption: 459.53 m³
  • Area: 1000 m²
  • HDD: 58

Step 1 – Weighted HDD by Area​

(41 × 10 + 58 × 1000) / (10 + 1000)
= (410 + 58,000) / 1010
= 58,410 / 1010
Weighted HDD = 57.83

Step 2 – Total Consumption​

500 + 459.53 = 959.53 m³
Total consumption = 959.53 m³

Step 3 – Specific Consumption​

959.53 / 57.83 = 16.59 m³ / HDD
Specific portfolio consumption = 16.59 m³ / HDD

Result​

✅ Specific consumption of the portfolio = 16.59 m³ / HDD

Summary​

  • HDD are not summed when aggregating
  • HDD are weighted by entity area
  • The result simulates a single large entity composed of multiple smaller ones