National Insulation Association

The National Insulation Association (NIA) represents the insulation industry in the UK.  Its members include manufacturers, system designers and installers of insulation solutions for your home or business.  Both the NIA and its members are fully committed to maintaining and raising standards within the insulation industry.

Find out more here.

Natural Ventilation

Natural ventilation occurs when air enters the building through openings to the outside world.  These could be open doors, opening windows or specifically designed vents.  If mechanical extraction fans are used without supply fans, the building is still naturally ventilated for energy assessment purposes.

The amount of natural ventilation that occurs in a building is measured through air-tightness testing.  This gives a values for the air permeability or air-tightness of the building which can be used to calculate the energy used to condition (warm up or cool down) the air entering the building.

Related Terms

Ventilation systems

Extraction systems

Mechanical ventilation

Mixed-mode ventilation


Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions.  Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

Nature’s mission statement

First, to serve scientists through prompt publication of significant advances in any branch of science, and to provide a forum for the reporting and discussion of news and issues concerning science.  Second, to ensure that the results of science are rapidly disseminated to the public throughout the world, in a fashion that conveys their significance for knowledge, culture and daily life.  Nature’s original mission statement was published for the first time on 11 November 1869.

Find out more here.


See National Insulation Association

Non-Domestic Building Services Compliance Guide

Approved Documents set out what may be accepted as reasonable compliance with the relevant Building Regulations in England to which they refer.  Following the guidance in an Approved Document establishes a presumption of compliance with the requirements covered by the guidance. However, compliance is not guaranteed.  The guidance may not apply if the particular case is unusual in some way.

The Non-Domestic Building Services Compliance Guide sets out the minimum standards expected for building services, their components and controls in buildings other than dwellings.  Further information and free pdf versions of the Approved Documents can be found on the Gov.UK website.

Other Approved Documents for England

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