low energy and solar solutions

Part L2A

Our Part L (Building regulations: Conservation of Fuel and Power) focus is primarily on new non-domestic buildings. Part L is divided into Part L1 which relates to domesic and Part L2 which is for non-domestic buildings. These are further divided up into A and B where A is for new buildings and B for existing buildings. Extensions to non domestic buildings may be assessed under Part L2A or Part L2B depending on floor area and its relationship to the area of the existing building. The accompanying notes refer only to Part L2A.

Part L2A is assessed on five criterion. The headings link to more detailed information on our services in these areas.

Criterion 1: Achieving an acceptable Building CO2 emission rate

This involves the calculation of a predicted carbon dioxide emission rate from the building and compares this with a building with identical geometry and functions but with nominal specifications similar to minimum standards. A naturally ventilated building will need to emit 23% less, an air conditioned/mechanically ventilated building 28% less than a building built to nominal specifications. A building incorporating some mechanical ventilation will have a target improvement in between these values depending on the proportion of mechanically ventilated zones. Emissions represent only those from providing the main building services (heating: space and water, cooling, ventilation and lighting).

Criterion 2: Limits on Design Flexibility

PartL2A describes minimum requirements for the following elements/systems

Criterion 3: Limiting the effects of solar gains in summer

Evidence is required that naturally ventilated perimeter spaces will not experience excessive gains from the combined effects of solar gains from sunlight, heat emitted from fixed lighting, occupants and equipment. Assessment is made based on

Criterion 4: quality of construction and commissioning

A building air permeability test constructed once the building is constructed, complete with any services which penetrate the envelope. Building Services will need to be commissioned and any ductwork will require pressure testing. Data from these tests is required in order to complete Criterion 1.

Criterion 5: Providing Information

This requires building log books for building owners/users to help them to run the buildings services in the intended manner. Part of the advice on this requirement is that the data used in the calculations for Criterion 1 is passed onto the owners.