Consequential improvements in construction

Consequential improvements refer to energy efficiency improvements that are consequential to changes to a building, which are required by regulation 28 of the Building Regulations (guidance for which appears in Section 6 of Approved document L2B: Conservation of fuel and power in existing buildings other than dwellings) to make the whole building comply with Part L of the Building Regulations

The regulation relates to proposed works to existing buildings (other than dwellings) with a total useful floor area of over 1000m2, and include:

• An extension.
• Installation of new fixed building services (other than renewable energy generators).
• Increasing the capacity of fixed building services (other than renewable energy generators).

Where such works are proposed, additional consequential improvements will be required to the extent that the necessary improvements are technically, functionally and economically feasible.

In most circumstances, this means that the payback period for the consequential improvements required does not exceed 15 years (or less if the expected life of the building is less than 15 years).

Consequential improvements could include:

• Upgrading heating, cooling or air handling systems.
• Upgrading lighting systems.
• Installing energy metering.
• Upgrading thermal elements.
• Replacing windows.
• On-site energy generation.
• Applying measures proposed in a recommendations report accompanying an Energy Performance Certificate.

In the case of an extension, the regulation can be complied with if the value of consequential improvements is not less than 10% of the value of the principal works.

In the case of changes to fixed building services, the building fabric should be improved so that the energy consumption of the services is not excessive, and additional consequential improvements must be made as described in the list above. Improvements to the building fabric in this case do not count towards the value of the consequential improvements. NB This does not apply if the services capacity is increased to supply a new extension rather than to improve services to an exiting space.

For changes to fixed building services, improvements to the building fabric are considered technically, functionally and economically feasible where the existing thermal elements have a U-value lower than those set out in the approved document. In the case of cooling, both the U-values of thermal elements and the solar gains of windows are set out, and in the case of lighting, an effective lamp efficacy is set.

Once the works are complete, the building owner should be provided with sufficient information to operate the building efficiently. This can be done by preparing a building log book.

NB Proposals to extend requirements for consequential improvements to dwellings (as part of the introduction of the green deal) were finally dropped by Communities Secretary Eric Pickles at the end of 2012.

[edit] Find out more

[edit] Related articles on Designing Buildings Wiki

• Building log book.
• Building Regulations.
• Energy efficiency of traditional buildings.
• Energy performance certificates.
• Energy targets.
• Environmental plan.
• Green Deal.
• Principal works.
• Sustainability.
• U-Value.

[edit] External references

• Approved document L2B: Conservation of fuel and power in existing buildings other than dwellings.