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Don't throw your money out the window. Calculate the efficiency of your ventilation system using Calc-Leak. Ingenium, an independent research and energy audit agency, developed a unique web tool, at Lindab's request, which can be used to map out the financial effects of substandard airtight sealing of a ventilation system. Calc-Leak was used to calculate the energy losses as a result of these leaks for a standard hospital, a nursing home for the elderly and an office building.

Calculation based on basic input. In the 'Basic input' section, enter the floor area for the selected building. Select the best air-tightness for the duct network (class D) and compare this with the standard value* (class 2.5A). Calculate both the payback period of the added investment and the annual energy saving.

Calculation based on detailed input. Do you want to know more and simulate a situation? As an HVAC specialist, you can take advantage of the 'Detailed input' option. The more information you know about your chosen ventilation system, the more precise your calculation will be.

Basic input

Building function
Floor area
Improved tightness duct system

Detailed input

Ventilation airflow
Surface area of ducts (supply & exhaust) (supply & exhaust)
Proportion of circular ducts (supply & exhaust)
Number of circular fire dampers (supply & exhaust)
Number of rectangular fire dampers (supply & exhaust)
Average diameter of circular ducts
Average dimension (Width or height) of rectangular fire dampers
Heat recovery
Moisture recovery
Power humidification
Power control fans
Total power of installed fans
Unit price electricity
€/MWh eVAT
Unit price fuel
€/MWh eVAT
Average static pressure drop in duct
Yearly price increase energy
Calculate Reset

Basic output

Cost reduction at exploitation
€/year eVAT
Extra costs for installation
€/year eVAT
Payback time

Detailed output

Energy consumption fans (supply & exhaust)
kWh electricity
Power demand cooling and dehumidification (supply)
kWh electricity
Power demand humidification (supply)
kWh electricity
Total electricity consumption ventilation
kWh electricity
Fuel demand humidification (supply)
kWh fuel
Fuel demand heating ventilation (supply)
kWh fuel
Total fuel consumption ventilation
kWh fuel
Total energy cost ventilation without leakage losses
€/year eVAT

Reduction Energy Costs

Improved tightness €/year eVAT Percent
From 2.5A to A 0.36 10.95
From 2.5A to B 0.53 15.82
From 2.5A to C 0.58 17.44
From 2.5A to D 0.6 17.98
From A to B 0.16 5.47
From A to C 0.22 7.29
From A to D 0.23 7.9
From B to C 0.05 1.93
From B to D 0.07 2.57
From C to D 0.02 0.66

Leakage loss calculations

Class Ducts
Fire Dampers
Air Flow
€/year eVAT
Class 2.5A 1 0 5 3 122
Class A 0 0 5 3 109
Class B 0 0 4 3 103
Class C 0 0 4 3 101
Class D 0 0 4 3 100
Without leakage loss 0 0 4 3 100

Reduction energy cost (Euro/year)

Reduction energy cost (percent)

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