Part L2A
Part L2A is assessed on five criterion:
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 building 28% less than a building built to nominal specifications.
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
external fabric: individual and area weighted U values.
Heating (and cooling if appropriate) plant efficiencies and controls
Pipework and ductwork insulation
lighting efficiencies
light switching
metering
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
detailed glazing specification, shading provided by the building, adjacent buildings and fixed shading devices
fixed values (CIBSE TM37) for occupancy and lighting based on space function
weather data for the region (CIBSE Guide A)
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.
Main Links
Part L2A links