All you need to know about…Part L of the Building Regulations.

Part L of the Building Regulations is the main legislative driver for improving energy efficiency in England and Wales. We examine the main points to consider when looking at heating technology.

Why is Part L important?

The government is committed to reducing greenhouse gas emissions by 34% by 2020 and 80% by 2050 (from base 1990 levels). It is hoped that renewable sources will make up 15% of the UK electricity mix come 2020, but the majority of carbon savings will have to come from simple energy efficiency improvements, predominantly on refurbishment projects.

The UK enforces the EU-wide Energy Performance of Buildings Directive (EPBD) via Part L (Conservation of Fuel and Power) of the Building Regulations. The latest amendments to Part L came into force in England and Wales on 1 October 2010. They represent an average 25% improvement in energy efficiency over the 2006 regulations.

The regulations are set to get progressively tighter. A further 25% improvement in energy efficiency will take place in 2013 and again in 2016. The EPBD includes a target to make all homes zero carbon by 2016 and all buildings by 2019.

Part L splits into four Approved Documents: L1A and B, plus L2A and B, covering new and existing domestic and non-domestic buildings respectively. Major refurbishments are covered as well as new build.

What has Part L got to do with boilers?

For the commercial sector, the Non Domestic Building Compliance Guide details how to meet the requirements of Part L of the Building Regulations. It goes without saying that all boilers (gas, oil or LPG) chosen must be of the modern, high efficiency type. The Regulations also allow other heat sources such as biomass boilers, heat pumps, CHP and electric heating.

The Guide operates a system of heating efficiency credits in terms of sizing, controls applied to boiler systems and so on – for example, keeping the boiler oversize to less than 20% of the full system load will earn you two credits.

The minimum boiler control strategy should encompass valved zone control, demand control via thermostats and timed control. Further credits can be achieved by applying various enhanced strategies to the boiler and heating system controls:

  • sequential control of boiler system;
  • thermostatic radiator valves (TRVs);
  • weather compensation of boiler system;
  • optimised start/stop of boiler system;
  • full zoned time control;
  • full building management system;
  • decentralising the heating system to avoid long pipe runs.

What is zone control?

Zone control means independent control of rooms or areas within buildings that need to be heated to different temperatures at different times. Where several rooms or areas behave in a similar way, they can be grouped together as a zone and put on the same circuit and controller.

What is sequence control?

Sequence control enables two or more boilers to be switched on or off in sequence when the heating load changes. This maximizes the efficiency of the boilers, so reducing fuel consumption and wear and tear on the boilers.

What is weather compensation?

Direct acting weather compensation is a type of control that enables a boiler to work at its optimum efficiency. The control allows the boiler to vary its operating flow temperature to suit weather conditions and the temperature inside the building. Weather compensation relies on communication between an external sensor and one inside the boiler. The boiler’s water flow temperature is varied accordingly, so that energy is not wasted by the boiler turning off.

Weather compensation via a mixing valve is similar except that the temperature of water supplied to the heat emitters is controlled by mixing the boiler flow and return rather than by altering the boiler temperature.

What is optimised start/stop control?

Optimum start is a control algorithm which starts plant operation at the latest time possible to achieve specified conditions at the start of the occupancy period.

Optimum stop is an algorithm which stops plant operation at the earliest possible time such that internal conditions will not deteriorate beyond preset limits by the end of the occupancy period.

How much energy will I save with these kinds of boiler controls?

Savings can be significant when correctly implemented. For example, good sequence control could save 5-10% of the overall energy consumption of the boiler plant. Most buildings with standard operating hours would benefit from installing optimised start/stop control. Again, savings of 5-10% could be achieved.

Where can I go for more information?

See www.planningportal.gov.uk/buildingregulations/

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