Calculation sheet

Project xxxProject Consultant xxxClient xxxxxContractor xxxxxSubject Staircase pressurization Air flow requirementLocation xxFan TypeDesign By xxx

Building DataFloor area 7250 m2Bilding perimeter 348.5 mFloor to floor height 5.95 mNote: Maximum diamentions are considered (i.e. perimeter is taken by )

Door DetailsDoor diamentions m m m2

A1 2.1 1.13 2.373A2 2.1 1.43 3.003Lift 2.1 1.2 0

Note: Put zero if the lift leakage is not considered

Building Leakage dataAccording to the Annex D of BS 5588 -4

Leakagearea ratio(A/Aw)

Exterior building walls Average 0.00021Lift well Average 0.00084Stairs/internal walls Average Internal 0.00011Lobbies Average InternalFloors Average 0.000052

A11A21

Calculation sheet

A. Calculation of air supply required for pressure differential with all doors closed, and stair, lobbies and lift well at 50 PaStairway leakageFrom doors

Door type Openingdirection

Leakagearea (m2) Qty

Resultantleakage

area (m2)

Single leaf in ward 0.01 1 0.01

Single leaf out ward 0.02 1 0.02

Single leaf in ward 0.01 9 0.09

From Walls

a (m) b (m) h (m) Leakagearea ratio

Leakagearea (m2)

6.7 2.7 49.35 0.00011 0.10216.7 2.7 4.9 0.00021 0.0193

Total leakage area 0.2414 m2Air supply required to raise stair to 50Pa 1.4168 m3/s

B. Calculation of airflow requirements with stair/lobby and lobby/accommodation doors open on fire floor, airflow of 2 m/sthrough lobby/fire room door, stair/lobby door open and lift door closed on floor below fire, accommodation vented on firefloor (mechanically), LL3 stair door to outside openNote: Though the code assume the lift door below the fire room is open, here that door is closed and leakage through that door is ignored

Air flow rate through lobby/accommodation door 6.006 m3/sPressure differntial across lobby/accomadation door with above flow 5.8064 PaAir flow through lift door 0 m3/s

Exterior wall wall diamentions

Door to roof

Door to evacuate

Door to lobby

Door

Interior wall wall diamentions

Calculation sheet

Total air through stair door (air through lift & lobby/accommodation door) 6.006 m3/sEffective area across stair and accommodation 1.86186 m2Pressure differntial across stair and accomadation with above flow 15.1 PaAir flow through LL3 stair/lobby door + lobby/accommodation door 6.005 m3/s

Calculation of leakage from stair wellleakage area through wall 0.1214 m2Leakage area through closed doors (including lift door) 0.17 m2 lift door + lobby /accmdation+Leakage area through side walls and floor of lobby below the fire floor 0.0052 m2Note: The maximum of floor to floor heights (i.e. 5.95m) is used.Air leakage through walls, closed doors, side walls and floors of lobby below fire 0.95662 m3/sPressure differential across stair and lobby of fire floor 9.2936 PaAir leakage through ceiling of the lobby below the fire 0.001566 m3/sNote: Pressure in side the lobby below the fire floor is taken to be equal to the stair pressure

Total flow rate required to the stair 12.96919 m3/sNote: According to the code, if the air for the airflow criteria > 1.5xthe air required for pressurizing the shaft,the 1.5 factor need not be applied. The ductwork leakage factor 1.15 is used

Total air requirement 14.91456 m3/s

floor)Air leakage through walls, closed doors, side walls and floors of lobby below fire 0.988873 m3/sNote: Added leakage through the LL3 closed door to air leakage through walls, closed doors, side walls and floors of lobby below fire of AAir leakage through ceiling of the lobby below the fire 0.001566 m3/sTotal air requirement 6.996439 m3/s

Air supply for pressure differential of 50Pa 1.4168 m3/sTherefore air flow through releaf vent 5.5797 m3/sReleaf vent area 0.950702 m2

Calculation sheet

D. Calculation of airflow requirements for conditions as in B except that the lobby/accommodation door on floor below firefloor is open (i.e. class E, phased evacuation, firefighting shaft)Note: The air supply requirements are the same as for B except that the lobby/accommodation door on thefloor below the fire is also open.Floor area 7250 m2Note: maximum of floor above the ground floor and floor below the ground floor is consideredLeakage area from floor and ceiling 0.754 m2Leakage area from walls 0.435451 m2Note: The maximum of floor to floor heights (i.e. 5.95m) is used.Total leakage area from building fabric 1.189451 m2Note: This area is in series with A1 and A2 (Lift leakage is ignored)Combined effective area 1.002363 m2

With 15.10 Pa in the lobby the air flow through this open door 3.232895 m3/sTherefore total air requirement 16.20208 m3/s

However, with only 1.4168 m3/s supplied for 50 Pa, an extra 14.79 m3/s has to be added to the stairway tosatisfy the airflow requirements, and a pressure operated relief vent of area 2.519226 m2 has to be provided in the stair to open air

With 1.15 factor, the total air requirement to the staircase 18.632 m3/s