All over H1

H1 Compliance in Existing Buildings

The Building Act 2004 requires all new building work to comply with the Building Code, whether a building consent is required, or the work is exempt. However, when carrying out building work on an existing building, it becomes a bit more complex

The Building Act 2004 requires all new building work to comply with the Building Code, whether a building consent is required, or the work is exempt. However, when carrying out building work on an existing building, it becomes a bit more complex

Alterations

When carrying out building work to alter an existing building, the new work must comply with current code and section 112 of the Building Act, which says the building as a whole must to comply with the requirements of the Building Code to at least the same extent as it did immediately before the building work began and not make it worse When it comes to H1 Energy Efficiency, in a nutshell, the performance of the existing building does not need to meet current H1 requirements but needs to be at least as good as it was before it was altered.

An example of this is an alteration where a new skylight is installed in an insulated roof. The R-value of the skylight must meet current code requirements, yet is still likely to be a lower R-value than that of the existing roof structure that it replaces. To ensure the overall performance of the building is not reduced, you will need to add sufficient insulation elsewhere in the thermal envelope to offset the loss in thermal resistance from the new skylight. This could be done by installing additional roof insulation in other areas.

Additions and extensions

For an addition or extension to an existing building, all new construction must meet current code including the requirements of clause H1, but the rest of the building that is not being altered does not have to be upgraded to comply with the current H1 requirements.

However, the altered building as a whole must continue to comply with clause H1 to at least the same extent as it did before the alteration. In other words, all new work must comply fully with current code requirements, and the energy efficiency of the building as a whole must not be diminished by the alteration.

If the energy efficiency performance of the building is reduced because of the addition or extension, you will need to upgrade some of the existing building to ensure the building performs at least as well as it did before the alteration. In short, once the work is completed, the building as a whole is not required to meet the levels set in the current H1 acceptable solution – it just needs to continue to achieve the level of thermal performance it enjoyed before the addition or extension.

An example of this is an extension of a living area, where an outer wall with one window and a timber door to outside is replaced with a wall of glazed bifold doors.

The R-value of the living area overall is likely to be less than it was previously, due to the addition of substantial glazing; even though the glazing will have to meet the current H1 requirements. To ensure the overall performance of the building is not reduced, you will need to add sufficient insulation elsewhere in the thermal envelope to offset the loss in thermal resistance from the new extension with significantly increased glazing. This could be done by installing additional roof or wall insulation in other areas or possibly by bringing other windows in the living area up to the current H1 requirements.

Repairs

For like-for-like repairs or replacement of a small part of the building envelope, such as replacing a window, door or weatherboards, you should simply ensure the overall thermal resistance of a building is not diminished. An example of this is the replacement of an older, single-glazed window or door. This can be replaced by a single-glazed window of the same frame material, as the replacement joinery will perform to at least the same extent as the one being removed and is not required to comply with the current code requirements.

Schedule 1 of the Building Act Exemption 1 allows you to repair, maintain or replace building elements without needing to obtain a building consent, provided a series of conditions is met.