29 August 2019

Energy efficiency standards

When selecting products and configuring solutions for a building we should be considering two key standards, these are the BS-EN15232 and eu.bac standards.
Being aware of these standards can not only reduce energy consumption but can improve user comfort.

Historic and common practice

Historically many buildings have been designed and built using good components, but final configuration means the building does not achieve its potential.
For example, rooms and spaces can have superb room controllers fitted but if they simply switch on in the morning and off at night with no consideration for occupancy or user based demand then energy is being wasted.
The use of demand based ventilation and devices such as presence detectors (PIR) terminal units is not always common place unfortunately.


The main challenge to delivering a good project can be “value engineering”, which generally means all the good elements are removed.

This type of issue often arises from projects being costed based on capital expenditure, however a key consideration is the operating costs of the building.
Considering only the capital expenditure only addresses short term costs whereas the operating costs of a building are a long term consideration.
If we can get the building user to understand the impact of changes on operating cost we can reduce the negative impact of “value engineering”.

We want to avoid short term small cost savings creating increased energy usage and higher operating costs over a building lifecycle.

Why use BS-EN15232?

There is a lot of detail in the BS-EN15232 standard, and I wont go into it all here, but you can broadly summarise the standard as meaning any energy source should only be used when there is a demand.

For example, a fan coil unit in a meeting room should only run in comfort if the room is occupied and in use, it should not simply be switched to comfort at the start of the day and potentially use energy all day despite the room not being used. 

Another example could be a school classsroom. The lights would be off until the teacher decides they need them on and switches them manually.
But during breaks and when the room is empty the PIR would switch the lights off after a short delay.

Finally, we could add CO2 into the mix and say that ventilation in a space would be increased based on CO2 levels adding a demand based element.

The key for all these scenarios is that the energy is only being used on demand, thus reducing operating costs.
That is the essence of BS-EN15232.

Why use eu.bac?

The eu.bac standard addresses energy consumption from a different angle.
It basically defines how accurately a controller controls the heating and cooling loops for a given room.

The end result is that a controller with good control accuracy will use less energy as it will maintain temperature better reducing how much heating or cooling is required.
This good quality control accuracy also ensures the space is maintained at a comfortable level reducing undesirable drifts from setpoint.
So eu.bac has a double benefit of energy efficency and improved comfort.

A key part of the eu.bac certification is that the whole loop is tested not just the controller, the test includes the sensor and valves.
This means that if a good controller is selected but cheap poorly operating valves are used then the eu.bac certification is then no longer valid.

Won’t using these standards cost more?

No! In pretty much all cases the standards can easily be achieved by good product selection and sensible configuration.
For example if a room has a PIR for lighting, use this to detect if the room is occupied and influence lighting and HVAC elements. 


When designing a system, ask a few key questions…
1. Can it be configured to acheive a high level of BS-EN15232 rating?
2. What is the eu.bac certification of the room controllers?
3. What impact will removing peripherals such as PIR’s have on the operating cost of the building?

When creating and selecting the strategies ensure that it is using demand based ventilation as much as possible.
In the future I hope to see BS-EN15232 a mandatory part of the building regulations rather than just a reference and comment for good practice.

The cheapest energy is the energy you do not use!

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