Why natural ventilation is best for power generation facilities: The facts and figures

Posted by Graeme Clark on 29/07/14 11:30

IMG_0782In my opinion, a natural ventilation system should always be the first choice for power plants, energy from waste, biomass, hydro stations, transformer stations and other similar buildings for 2 reasons:

1) The Environment 

The number and frequency of extreme weather events has been on the increase throughout the world. The climate is changing, of that there is no doubt, and the most popular theory is that this is due to the rise in CO2 emissions. 

We all know that natural systems use less energy than mechanical systems, but have you ever quantified the environmental impact? Let’s look at a project example - a typical biomass boiler hall with a 500kW heat load. In this instance:

  •  A mechanical ventilation system would require an extract fan rated at 22m3/s with a 24kW motor.
  • This extract fan will use approximately 157,680kWh of electricity per year (assuming that the system will be operating 75% of the time).
  • Using the Carbon Trust conversion factor, this extract fan would generate 70,243 kg of CO2e per year.
  • A mature tree can absorb approximately 24kg of CO2 per year.
  • Therefore it would require 2,927 mature trees to absorb the CO2created by this mechanical extract fan every year!
  • A natural ventilation system would create no CO2 emissions!

2) Cost

Keeping with the example above, let’s now compare costs:

Supply and Installation Cost

  • Mechanical Ventilation                  -              £25,000
  • Natural Ventilation                         -              £50,000

Running Costs

  • Mechanical Ventilation                  -              £15,768 per year (assuming 10p per kWh)
  • Natural Ventilation                         -              £0 per year

Combined Cost over 5 Years

  • Mechanical Ventilation                  -              £103,840
  • Natural Ventilation                         -              £50,000


Natural ventilation is not only better for the environment, but it will also save your client money – and probably a lot of it over a 25 year period!

Designing a natural ventilation system can be a daunting task. Weathered, attenuated and controllable ventilation is normally required for such buildings. It can be a complicated process to calculate the Cv (coefficient) of the combined equipment and determine the number of ventilators and their position to meet the design requirements, so we recommend that you take advice from a natural ventilation specialist. They should be able to offer free design (make sure it includes guarantee of performance), CFD modelling, product selection/sizing/integration, and controls.

If you want to know more, you can find further information in our other articles on ventilation relating to power generation facilities, or contact me using the links below.

Graeme Clark Graeme Clark is a Senior Consultant for Colt UK and specialises in the design and product application of energy efficient HVAC and smoke control systems.

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Topics: Natural ventilation, Energy saving, Climate Control, Power Plants