28 August 2019

Seasonal Compensation in Modern Buildings.

There is no getting away from the fact that buildings consume energy, but we can reduce the amount of energy they consume and make them more energy efficient.
And the key is in many cases the improvements come down to the strategies implemented and don’t need new hardware.
For this blog article I want to consider one strategy that seems to have fallen out of use…
Seasonal compensation for room control.


When I first started out in the building controls industry and worked on terminal units for room control most buildings had seasonal compensation at room level, and this is looking back 30 years. However, over time this control strategy seems to have fallen out of favour for some reason.

Seasonal compensation is great as it changes the base setpoints of the terminal unit to reflect the outside temperature.
What this means is that in winter the setpoints in the rooms should be lowered, and in the summer the setpoints should be raised. Whilst this may sound counterintuitive the reason is that this operation reduces the thermal shock when entering buildings.

For example when it is 30°C outside entering a building with room control set to 21°C can feel very cold, but entering a building set to 24°C is still cooler and more comfortable, but is using less energy and is less of a shock to the body.
The same can be found in winter. When it is 10°C outside entering a building at 22°C can feel very warm, a building set to 19°C or 20°C would feel much more comfortable, less of a shock and use less energy.


The first challenge in our modern working environment is managing peoples expectations. We need to get to a stage where people accept a much wider range of temperatures in their buildings if they want to see energy consumption reduced.

In most buildings the setpoints tend to be around 21°C for heating and 23°C for cooling or in some cases even 22°C for cooling.
We need to see building owners and companies pushing to have staff accept a wider range of setpoints, maybe get people to accept that a space will be between 19-23°C or even 19-24°C during normal occupation.
Once that is in place using seasonal compensation of setpoints is easily applied.

The second challenge is making sure strategies such as seasonal compensation are specified in a building design. This means we need to influence and educate building specifiers to ensure they apply such schemes in their specifications.

Finally, it comes down to trying to make sure the operating costs of a building are considered when planning a project as small investments in capital expenditure (i.e. CO2 sensors and PIR’s) can lead to long term savings on operating costs.


Seasonal compensation is just one part of the story, we then need to consider using other strategies such as CO2 measurement and presence detection to ensure we use a demand based control system and only switch on room controls when needed. Use those along with switching terminal unit fans off in the deadband and the energy savings can be substantial.


Lets not design and deliver mediocre buildings that don’t address the environmental concerns we all have, lets make sure we design and promote buildings that use strategies designed to reduce energy consumption.
In most cases it is software not hardware that is needed, but where adding sensors such as C02 or presence is needed the payback is easily achieved over the lifecycle of the building.

For more visit: www.siemens.co.uk/buildingtechnologies

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