Changing Office Use in the Course of Corona – Energy-Efficient Operation of Office Buildings

Due to the Corona pandemic, many companies have increasingly relied on home office since spring 2020 and have simultaneously seen a significant reduction in building occupancy. Depending on the industry, it is also becoming apparent that this trend could continue in the future and occupancy may never return to the pre-Corona level. This presents new and significant challenges for both the technology as well as the personnel to continue to provide energy efficient building operations against this backdrop. The following are excerpts of the FfE’s findings from recent energy audits.

Intelligent operation of ventilation systems

One of the main energy consumers in office buildings is often the ventilation and air conditioning system, including heating and, if necessary, cooling of the usable areas. To optimize this, it makes sense to review the operating times and adjust them to the new demand – as well as the required temperature level or the heat recovery in the system.

In order to continue to ensure energy-efficient building operation of ventilation systems with low building occupancy at the same time, one option for action is to decouple unoccupied building sections or floors from the active room air supply, for example, with the aid of shut-off dampers. For these areas, only a basic air exchange then takes place instead of the regular air volume flow. In this way, the total air volume flow of a ventilation system can be greatly reduced and, as a result, the electricity, heating and, if necessary, cooling requirements can be significantly reduced.

The following figure 1 shows a schematic diagram for a multi-story office building with different installation locations of a ventilation system. In the example, shut-off dampers are positioned in such a way that the supply and exhaust air ducts can be shut off for all floors depending on the building occupancy.

Figure 1: Exemplary Positioning of shut-off dampers for decoupling building levels

Within the scope of an energy potential analysis of a 4-story office building with a nominal volume flow of the supply air of about 20,000 m³/h, the following savings potentials were determined, for example:

  • By shutting off the most distant floor to the ventilation system, the nominal volume flow could be reduced by about 16 %, which would reduce the heat demand by the same amount and the electricity consumption by about 40 %. Accordingly, there would be an energy cost saving of about 5,500 €/a.
  • Should only one floor continue to be primarily required due to increased home office, the nominal volume flow could be reduced by just under 60 % by shutting off all other floors, which would reduce the heat requirement analogously by the same amount and the electricity consumption by over 90 %. This would correspond to energy cost savings of over 16,000 €/a.

In order to be able to decouple individual areas from the HVAC supply according to demand, it is necessary to introduce an intelligent seating plan booking system with which the employee occupancy in the individual parts of the building can be controlled. In the case of office buildings, the goal is to first occupy the area of the building that is in the closest proximity to where the ventilation system is installed and to supply it with media in the normal state (see Figure 1). If a ventilation system is installed on the roof of an office building, for example, the top floor should also be occupied first, while the areas below should only be successively occupied as necessary to remain compliant with company Corona policies. In this way, the partially-occupied office building can be supplied with room air in a much more energy-efficient manner.

Standby consumption at office workstations

Another area of optimization for energy-efficient building operation as a result of Corona is the reduction of standby energy consumption at office workstations, which may contribute significantly to base load consumption. This can be achieved by equipping workstations with intelligent multiple sockets – so-called master-slave sockets. In this way, it is possible to reduce the year-round standby consumption of equipment (e.g. docking stations with monitors) to the socket’s own consumption and save large proportions of the power consumption which originates there. Intelligent multiple sockets mean that when, for example, the monitor goes into standby mode, the other devices connected to the socket can be switched off automatically. The revenues that can be generated by this can amortize the investment costs within a very short time (up to less than a year).

It turns out that even with reduced use of office buildings due to increased home office, there are some economically interesting opportunities to continue optimizing the energy efficiency of office buildings.

The FfE’s industry team will be happy to assist you in identifying company-specific energy-saving potential and deriving suitable measures for its implementation. Please do not hesitate to contact us if you have any questions.

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