D11 and D12 of the EMS record collect information on the GIA and NIA of the institution. 

What is GIA?

Gross internal area (GIA) is the total area of buildings owned, occupied or maintained by the HEI measured to the internal face of the perimeter walls at each floor level (i.e. the footprint of the building excluding the width of the outside walls). It includes areas occupied by internal walls and partitions. 

What is NIA?

Net Internal Area (NIA) is the usable area within a building measured to the internal face of the perimeter walls at each floor level. NIA covers all areas which are used for a specific purpose.

NIA includes:

• Teaching and research rooms
• Offices
• Kitchens
• Workshops
• Built-in units, cupboards etc. occupying usable area
• Stores
• Academic stores
• Changing rooms and showers (e.g within or as part of clean rooms, catering facilitie, sports facilities)
• Porters' offices and kiosks
• First aid rooms
• Staff common rooms
• Internal partition walls (e.g. fixed walls, de-mountable re-movable screens)
• Ramps of lightweight construction to false floors
• A floor area which contains a ventilation/heating grille
• Area occupired by skirting and perimeter trunking
• Areas severed by internal non-structural walls, de-mountable partitions (whether or not permanent) etc. where the purpose of the division is partition of use (and not support) provided the area beyond is not used in common (by more than one occupier)
• Pavement vaults
• Notional lift lobby and similar areas, where ther are several functions using the area, such as meeting space, reception or cafe.
• Accommodation on NHS sites which is maintained or paid for.

It does not include those parts of buildings which enable them to function, such as corridors. These are classified as balance areas. (See What are balance areas? below).

Approaches for defining NIA

There are two alternative approaches for the return of data on net internal area (NIA):

• NIA RICS (Royal Institution of Chartered Surveyors) basis
• NIA room area

1. NIA RICS basis
The NIA RICS definitions are contained in the 'Code of Measuring Practice: A Guide for Property Professionals' (Sixth Edition), published by the RICS. This method involves the measurement of the internal room area part way into the width of internal walls and partitions.

This is the preferred method of measurement and is demonstrated by the left-hand room in the diagram below.

2. NIA room area basis
This method involves the measurement of the internal room area less the widith of internal walls and partitions.

This is the less preferred method of measurement and is demonstrated by the right-hand room in the diagram below.

Uplifting NIA room area

HESA captures detail of the NIA measurement method used in D13. Where the NIA room area basis is used HESA will apply a 6% uplift to the NIA measurements returned in D12. Application of this uplift is necessary to ensure that the EMS ratios use a consistent value of internal area across the sector.

What are balance areas?

Balance area is the floor area provided as part of the GIA to enable the building to function.

Balance area should be excluded from the NIA calculations.

The following are examples of balance areas:

• Corridors and other circulation areas of a permanent nature (e.g. fire corridors, smoke lobbies, etc.)
• Internal open-sided balconies or similar
• Internal structural walls, walls enclosing excluded areas, columns, piers, chimney breasts, vertical ducts and other projections
• Stairways and stairwells (and voids over)
• Entrance lobbies (where the function is solely or primarily for entry/circulation)
• Foyers (where the function is solely or primarily for entry/circulation)
• Atria with clear height above, measured at base level only (where the function is solely or primarily for entry/circulation)
• Lifts
• Permanent lift lobbies, permanent lift rooms, liftwells and lifts (and voids over)
• Lavatories and toilet lobbies
• Cloakrooms
• Cleaners' stores
• Cleaners' cupboards (as defined in the RICS definition)
• Covered areas e.g. plant rooms, tank rooms, fuel stores which are housed in a structure of a permanent nature, whether or not above main-roof level.
• Loading bays
• Ducts
• Permanent and continuous air-conditioning, heating or cooling apparatus (as defined in the RICS definition)
• Boiler houses
• Calorifier chambers
• Fuel stores

Therefore in the diagram below the balance area is that which is not contained within the red box. The area contained within the red box is eligible for inclusion within NIA. The area lying outside of the red box is excluded, i.e. the corridor and lavatory.