Ducted Distribution of Services

QUS 3206 / MDM NURUL AINI

Ducted Distribution of Services

• Service duct require careful planning and should be considered at an early stage in the design of a building.

• Accommodation of the plant and the layout of services are the two essential factors in design.

• It is usual to need some 7 – 10% of the total floor area for plant spaces and ducts.

Ducted Distribution of Services

• The purpose :• conceal the services and to facilitate inspection,

repair and alterations. • Helps to reduce noise• Protects the services from damage

Terminology • Plant space – area required for the

accommodation of mechanical or electrical equipment or control gear required for the operation of services

• Storage space – area required for the accommodation of storage containers required for particular services

• Duct – space within a building specially enclosed for the accommodation of services and allowing facilities for working and inspection.

Terminology • Subway – a horizontal passage for the

conveyance of services underground or below the bottom floor of the building which allows walking headroom for access.

• Crawlway – passage for services similar to a subway but where there is insufficient headroom to stand upright.

• Trench – horizontal passage for services below floor level where the access is by removable covers in the floor.

Terminology • Wells – vertical space used for the

accommodation of stairs or lifts or to allow natural light or ventilation • Casing – an enclosure formed over

pipes or cables running on the surface of a wall or ceiling. Casing are usually for decoration but can also provide protection from impact or corrosion.

Terminology • Chase – a recess cut in a wall or

floor when building is over; it accommodates pipes or cables and is screed or plastered over

• Void – space may used for the accommodation of services but which is not primarily for this purpose

Ducts for Small pipes or cables• These may be formed in the floor or wall, or on

the surface of the wall.• The size of ducts depends upon the outside

diameter of the pipe or cable and the number of services installed.• Normally the outside diameter not exceeding

64mm

• Casing & Chase

Terminology • Sump – pit for seepage, leakage and draining

down of pipework that cannot be discharge by gravity to the drain and must be collected and pumped.

• Trunking – lightweight, usually sheet metal enclosure for the passage of air or cables

Terminology • Flue – builders’ work or metal passage to

convey the products of combustion to an acceptable point for discharge to the atmosphere

• Service core – zone extending vertically through high rise building containing vertical circulation, service ducts and other utility and sanitary provisions.

Important of unified system of services distribution • Most services can be run in common ducts except flammable

liquids and gases • The pattern of distribution of services is considered as a whole in

relation to the building planning• 3 different categories of services run having different requirements

for patterns of distribution: • Wells and flues• Pipes and ventilation trunkings • Electrical cables

• Stair and lift wells run vertically through buildings. They do not required linkage with services at each floor level but prevent an obstacle to horizontal distribution of other services

Location and approximate sizing of plant spaces and ducts

• Different building functions will imposed different priorities on the service

• Electrical cables do not normally imposed serious limitations on planning however the length of cables may be a dominant factor

Location and approximate sizing of plant spaces and ducts – Planning considerations

Air trunking • large and essential to consider

them at the outset of any design • They must be take into

consideration first before other services due to the space requirement

Waste and soil installation • Are not as large as air trunking but

need to be design in the early stage due to space requirement

Location and Approximate Sizing of Plant Spaces and Ducts Heating pipes • May be larger than waste and soil pipes in

large buildings due to the insulation but generally they are smaller in size.

Water supply pipes • Are very often smaller than heating supply

pipes and do not require heavy insulation.• They are equal flexible in their detailed layout

and may be taken up and over or under obstruction without any major problems.

Location and Approximate Sizing of Plant Spaces and Ducts

Electrical cables • Very small in most buildings and they can

very easily be accommodate in comparatively small trunking

• They are disposed within the thickness of a floor screed

Approx. sizing of ducts:

Several factors to consider in deciding the size of ducts and recess: • Number & size of pipes, cables & trunkings to be accommodated • Any critical spacing or fixing position which must be followed for certain

pipe types • Clearance required for placing the pipes in position, which must also allow

for ease of removal should it become necessary during maintenance• Clearance to allow for position of fixings and to permit jointing

Approx. sizing of ducts:

Several factors to consider in deciding the size of ducts and recess (cont’d): • Allowance for additional services which may be needed • Space for access in the case of ducts• Space of valve, dampers • Space for expansion bands in long, straight horizontal or vertical ducts • Space for branching and service junctions, and to carry these branches

past adjoining services

Vertical ducts & Underground ducts

• Vertical ducts – dimensions are often found varied due to lack of planning in the design process

• Underground ducts – would conflict with columns and foundations in construction

Vertical Duct

Underground ducts

Ceiling voids • Space to accommodate services within the ceiling void but near the

points at which branches leave the primary vertical ducts to enter secondary ceiling recesses, the trunking and pipes will be at their maximum diameter and the necessity for crossing will be relatively high

• Headroom on the various floors will be normally have been reduced to the acceptable minimum

• Space available above suspended ceiling will also kept as low as possible, in order to avoid increasing the overall height of the building.

Service distribution above ceiling

Floor voids

• Increasing use of electrical, telecommunications and computer equipment in office has led to the use of suspended floors to contain wiring and provide flexibility for additional and alterations.

Crossing services & Space around trunking

Crossing services – where services cross it is possible to have a great deal of wasted space in ducts

Space around trunking – cable trays suspended from ceilings should have minimum clearance of 250mm at each side and similar distance above each edge of the tray

Location and Approximate Sizing of Plant Spaces and Ducts

Ventilation trunking • Ventilation trunking should have 250mm clearance of the

sides and at least 300mm clearance above the trunking • The clearance above the trunking should be increase up to

500mm for 2m wide trunking

Fire hazards • Vertical ducts should have vents at the top so that smoke and

flame can be dissipated • Ducts must be sealed where they pass through fire resisting

construction • The walls and doors of the ducts must have adequate fire

resistance • Pipes run through fire-resisting walls should have gaps tightly

packed with fire stopping material and depending on the movement of pipe

Duct details

• All major underground ducts should provided with channels to carry away seepage and leakage

• Vertical duct – simply a recess in corridor wall covered by ply facing

Duct details• Some have to laid to fall – drainages • Firmly support – heating/ or water pipe with pressure to avoid

movement • Long and straight lengths pipes – adjustable level pipe clip • Underground ducts – provide with channel to carry away

seepage or leakage • Access to the services – maintenance

TUTORIAL 1.Choose any one (1) department/building/faculty in Inti IU e.g. library. Provide photographic evidences to identify various ducting system in Inti IU Building.

2. Explain the important of adopting unified system of service distribution.

3. Explain the factors that must be considered in deciding the size of the ducts and recesses.

Due Date : …………………………………Task :