Getting to grips with existing buildings
Head of Technical and Safety Bob Towse explains what ‘consequential improvements’ are, clears up some misconceptions and sets out how they may apply to your projects.
Part L is the section of the Building Regulations concerned with Conservation of Fuel and Power. During an overhaul of the regulations in 2006, the concept of consequential improvements was introduced, and further changes were made in 2010.
In the past, Part L only required minimum standards for elements of work actually being carried out. For example, minimum efficiencies for replacement boilers, and maximum U-values for walls and windows in extensions.
Under the current Part L, when certain types of work are carried out, not only do elements of the principal works need to meet minimum standards, but also improvements may need to be made to the energy efficiency of other parts of the building as a consequence of this work. Hence the term consequential improvements.
However, in the 2010 regulations, consequential improvements only apply to existing buildings over 1,000m2, so most homes are not affected. Also some extensions to buildings are treated as new buildings for the purposes of compliance, but consequential improvement may still be triggered - see flowchart below.
There are two categories of principal works which may trigger a consequential improvement:
Increase in habitable area
This applies to principal works such as the extension of an office building, or the construction of a mezzanine inside an existing retail store. Energy efficiency improvements have to be carried out to the whole building, up to a value of 10% of the value of the principal works.
These improvements could include:
- Replacing boilers
- Upgrading lighting
- Energy Metering
- Upgrading building fabric
- Increasing the contribution of
Increasing the installed per unit area capacity of building services
This applies to principal works such as adding radiators to a space that is underheated, or installing air conditioning in an office building for the first time. The term “installed capacity” relates to the terminal units, not the central plant. So, for example, replacing a 400kW chiller with a 500kW chiller would not trigger a consequential improvement.
If consequential improvements are triggered, the first necessary step is to reduce the required capacity of the service. For example, in the space where additional radiators are proposed more wall insulation could be installed, and in the office building where air conditioning is installed for the first time solar shading could be added.
Secondly, energy efficiency improvements have to be carried out to the existing building, up to a value of 10% of the value of the principal works. This 10% is on top of any money spent on reducing the required capacity of the service.
Economic, technical and functional feasibility
However, there is an overriding rule about consequential improvements: They must be practically and economically feasible.
It would be up to the applicant to demonstrate to the building control authorities that a particular improvement was not feasible. For example:
- If a roof cannot safely support the weight of additional insulation, the applicant could reasonably argue that this improvement is not technically feasible.
- If additional floor insulation would result in a change in floor levels between different parts of the building, the applicant could reasonably argue that this improvement is not technically feasible.
- If the cost savings from installing a more efficient boiler do not recoup the cost of installing that boiler over a 15 year period, the applicant could reasonably argue that this improvement is not economically feasible.
Any improvements that do not have a 15-year payback, or less, can be eliminated.
Consequential improvements are therefore more likely to affect older, less efficient buildings or those where energy efficiency improvements have already been made.
For more information visit the Part L website here.
Frequently Asked Questions
Q: I’m building a loft extension to my home. Do I need to carry out consequential improvements?
A: No, not unless you live in a house over 1,000m2 floor area.
Q: I’m doing a refurbishment of an existing office building. Do I need to carry out consequential improvements?
A: No, not unless you’re increasing the habitable area or increasing the installed per unit area capacity of building services.
Q: My building gets too hot in the summer, and I’m considering putting in additional air conditioning units. Do I need to carry out consequential improvements?
A: First of all, see if you can deal with the overheating problem without resorting to additional air conditioning. Try solar control glazing, night purge ventilation, more efficient lighting, or relocating heat-producing equipment away from occupied spaces. Following the recommendations in your annual air conditioning inspection report may solve the problem. If you find that you have to install additional air conditioning, then yes you will probably need to carry out consequential improvements, providing they are economically, technically and functionally feasible.
Q: I’m building an extension, and building control have told me I need to spend 10% of the value of that extension on improving the energy efficiency of the existing building. There isn’t enough in the project budget to pay for this. Can I argue that these improvements aren’t economically feasible?
A: No. You can only argue that an improvement isn’t economically feasible by showing that it has a payback of more than 15 years.
Q: I’m building an extension, and I’m also planning on replacing my 20-year-old chillers. Can the chiller replacements count as a consequential improvement?
A: Yes, consequential improvements can be something you were planning on doing anyway.
Q: I have looked at all the possible consequential improvements to my building, and I can’t find a single thing that will pay for itself within 15 years. Do I still need to carry out consequential improvements?
A: No. Clearly your building is already quite energy efficient. You may choose to do some improvements that have a longer payback, but you can’t be forced to do so. The whole point of consequential improvements is to require owners of less efficient buildings to put some budget aside for energy efficiency improvements whenever they’re spending money on certain enhancements to their asset.
Q: Why bother when I am only replacing the radiators?
A: Approved Document ADL2 does not exclude certain works. If the principle work meets the criteria, the work is not fully compliant until the consequential
improvements have been made.
Q: Who is responsible for compliance if there is work included in possible measures which would not normally be carried out by HVCA contractors, such as replacing glazing or adding insulation?
A: We take the view that it is the contractor’s responsibility to inform – preferably in writing - the client that additional works may be needed in order to comply with the conditions relating to consequential improvements, but the client is responsible for completing the further works.
For more information visit the Part L website.
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