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INFORMATION - VENTILATION FOR SCHOOLS

Ventilation on demand has a background in adapting ventilation to need rather than supplying ventilation "blind". We don't leave the vacuum cleaner on all the time to occasionally suck up dust; we don't drink a glass of water an hour to avoid getting thirsty, and we don't leave the tap running constantly because we sometimes wash our hands. So why should we ventilate a building regardless of whether there is anyone in it or not?

The result of tradition and laziness
Of course it's as a result of a lack of knowledge and products, and due to tradition and low energy prices that we have acted in this way. But when it now turns out that the overall level of occupancy in a typical office building is a maximum of 60% (average level approx. 35%) and that people work in the evening and at weekends, we realize that it is perhaps not a good idea to run the ventilation system "On/Off" controlled by the clock.

New technologies alter the rules of the game
Technologies now exist to adapt ventilation and the indoor climate according to need, so it's really simply a matter of realizing that a property doesn't need to use 143.5 kWh/m2 per year (according to the Swedish Energy Agency's STIL research) but that it can actually have extremely satisfied tenants with an energy use of only 53 kWh/m2 per year, even if it was built in the 1960s and doesn't have insulation as thick as the Great Wall of China.

How can we reduce our energy bill?
The fact that new construction is today carried out to achieve low energy consumption is today self-evident. Tenants demand it, and property owners want to save money. However, it's not new constructions using 41 kWh/m2 per year that will reduce Sweden's energy bill, but rather the renovation of existing building stocks. Simple energy efficiency measures equate to picking the low-hanging fruit – this can mean looking over operating times on air handling units, reviewing thermostats and perhaps replacing armatures. Larger-scale measures can be perceived as difficult. They can necessitate temporary premises if they cannot be carried out during tenancy changeovers. There is perhaps no digital documentation, so time and effort can be required to carry out the inventory and design stages.

Qualitative factors – difficult to quantify?
However, an energy renovation project has several positive aspects in addition to sheer reduction of operating costs:

  • Improved indoor climate – perhaps you can install the cooling system that was always lacking 
  • Better comfort leads to the possibility of increased rents 
  • The tenant becomes more effective in their work A temperature that is too high or too low by 4 degrees reduces a person's efficiency by approximately 5%, and more air increases efficiency by approximately 3%. Surely every MD would make changes in their company that would increase personnel efficiency by 3%?
  • A property equipped with modern installations can be monitored via the Internet, which reduces the costs both of operation and maintenance. Ongoing optimization and troubleshooting can be carried out in a fraction of the time it used to take.
  • New ventilation solutions are quieter. This reduces the costs of sickness absence caused by stress and noise.
  • New technology, better comfort, lower operating costs, more interesting premises for tenants, reduced vacancy and increased property values as a result.


Even if there are clear profits that are not visible in the investment calculation, the above factors should be considered. In terms of experience, we tend to look only at costs and energy savings and what then becomes decisive for keeping down the costs and thereby obtaining a good return on the investment is the possibility of retaining the existing duct system and avoiding putting a lot of new electricity cabling.

Existing duct system
To avoid temporary premises and expensive rebuilding of the duct system, it is clear that it is important to be able to retain the duct system. This requires the supply air diffuser to be able to work over a large flow range in order to satisfy indoor climate requirements and be energy-efficient, but also to be able to handle reducing a large static pressure since a slightly too restricted duct system will experience dynamic pressure drop losses during higher flows. This has led us to develop a product that can handle a typical cellular office layout with cooling requirements of approx. 500 W, and does so with a low noise level of 35 dB(A) even on high pressure of 200 Pa.

Occupancy Jan.-Sept. in office property (max. level approx. 50%)

If there is nobody in the property, the ventilation should be shut off to save energy. In the same way, a full building requires a lot of ventilation. The number of people actually in the property is therefore extremely important. It is also extremely important in determining the total cooling and heating capacity that must be available. Demand control is of course dependent on this level of occupancy.

We therefore have in-built occupancy detectors in each diffuser so that we get really good information about this level of occupancy both on a room level and on an aggregate level for the whole property.

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