Building envelope

According to Approved Document L2B: conservation of fuel and power in existing buildings other than dwellings, the term 'building envelope' refers to:

Together, these form the physical separation between the interior and exterior, that is, the climatic modifier that creates and contains the internal conditions.

The nature of the building envelope is likely to depend on a wide range of requirements, some of which may be in conflict:

• The type of building.
• Its location and context.
• Its form.
• Regulatory requirements.
• Local climatic conditions.
• The internal conditions required.
• The need for openings, views, security, safety, access, privacy and so on.
• Available materials.
• Structural requirements.
• Building services strategy,
• Sustainability requirements.
• Maintenance and cleaning requirements.
• Rainwater run off.
• Durability, flexibility and expected life.
• The method of construction, deconstructability and recyclability.
• Stylistic requirements.
• Budgetary and time constraints.

NB According to Approved Document L1A:

And, in relation to air permeability:

National Calculation Methodology (NCM) modelling guide (for buildings other than dwellings in England) 2013 edition, published by the Department for Communities and Local Government (DCLG), defines ‘envelope area’ as:

Energy Efficiency and Historic Buildings, How to Improve Energy Efficiency, Published by Historic England in 2018, defines the building envelope as:

[edit] Related articles on Designing Buildings

• Air permeability testing.
• BCIS elements.
• BRE Building Elements series (AP 243).
• Elements of structure in buildings.
• Floor.
• Roof.
• The building as climate modifier.
• Types of wall.
• Windows.
• Doors.