When a building has many rooms, several floors or a design that does not suit wall-mounted units, a central system is worth considering. In Lahore the two common routes are ducted central AC and VRF (variable refrigerant flow, also sold as VRV). Both need planning before ceilings, shafts and roof space are fixed.
What is included
| Item | Ducted central AC | VRF system |
|---|---|---|
| Outdoor equipment | One or a few large units or a chiller/packaged plant | One or more outdoor modules serving many indoor units |
| Indoor equipment | Air handling unit or large ducted unit | Many indoor units: ceiling-concealed, cassette, wall or floor |
| Distribution | Sheet-metal or pre-insulated ducts, grilles and diffusers | Refrigerant copper pipes with branch joints; short ducts if concealed units are used |
| Controls | Thermostats, zone dampers if zoned | Individual controllers per room, central controller option |
| Fresh air | Fresh air intake into the system | Separate fresh air unit or ventilation, if designed |
| Design | Heat-load calculation, duct sizing, equipment selection | Heat-load calculation, pipe sizing, branch layout, equipment selection |
When you need it
- Larger houses (often 1 kanal and above) where many outdoor split units would crowd the roof or elevation
- Offices, clinics, showrooms and restaurants
- Multi-storey buildings where a central plant room or roof bank is practical
- Interiors where visible wall units are not wanted
Step-by-step process
- Brief. Share architectural drawings, room use, occupancy and working hours.
- Heat-load calculation for each room or zone by the HVAC designer.
- System proposal. Ducted or VRF, with equipment capacities, indoor unit types and outdoor location.
- Coordination with the architect and structural engineer for ceiling depth, shafts, roof loads and plant space.
- Electrical coordination. Total load, panel and cable sizing; LESCO load extension if needed.
- Shop drawings for ducts or pipe routing, approved by you or your consultant.
- First-fix installation of ducts or copper and drains before false ceilings close.
- Equipment installation, pressure testing of pipes, vacuuming and charging.
- Testing and commissioning room by room, with airflow and temperature checks.
- Handover with as-built drawings, warranty papers and a maintenance schedule.
Approvals and rules in Lahore
The LDA Building and Zoning Regulations (LDA regulations) set rules for ducts in buildings other than houses:
- AC and ventilation ducts must be non-inflammable and adequately supported.
- Where ducts pass through walls or floors, the openings must be sealed against flame and smoke.
- Fire dampers are required where ducts serve two or more floors or pass through walls.
- Air intakes must not draw air from spaces with inflammable vapours or dust.
The same regulations relax internal daylight rules for rooms where permanent mechanical air conditioning is provided. For larger buildings, also check the roof load of outdoor equipment with your structural engineer; above 38 feet, LDA requires structural calculations vetted by an LDA-panel engineer. DHA and private societies may have their own rules on roof equipment and elevations.
What affects the cost
We do not list prices because they depend heavily on equipment and building. Get itemised quotes. Cost depends on:
- Total cooling capacity and number of zones
- Ducted vs VRF, and indoor unit types
- Duct material and length, or copper pipe length and branch count
- Insulation spec
- False ceiling and access panels (often by another trade)
- Controls: individual, central, remote monitoring
- Fresh air and exhaust integration
- Crane or lifting for roof equipment
- Electrical works and panels
- Annual maintenance contract
Questions to ask the contractor
- Who did the heat-load calculation, and can I see it?
- Is the design engineer registered with the Pakistan Engineering Council?
- What ceiling depth do you need for ducts or concealed units?
- How is fresh air provided?
- Which items are excluded (false ceiling, electrical, civil work, crane)?
- What warranty covers equipment, and what covers your workmanship?
- Will I get as-built drawings and a maintenance plan?
Red flags
- Equipment selected without a room-by-room load calculation.
- No shop drawings before work starts.
- Ducts or pipes installed after ceilings are planned, with no coordination.
- No fire dampers proposed where ducts pass between floors in a commercial building.
- No pressure test record for VRF piping.
- A single lump sum with no breakdown of equipment and materials.
FAQs
Is VRF cheaper to run than many split ACs? It can be, especially when rooms are used at different times, because the system adjusts output. Running cost depends on design, use and maintenance. Ask contractors to explain the basis of any savings claim.
Can I add central AC to an existing house? Often yes, but ducts need ceiling space. VRF with concealed or wall units can be easier to retrofit. A site survey will tell.
Do I need a plant room? Many VRF systems use outdoor modules on the roof. Larger ducted or chilled-water systems may need a plant room. Your designer will advise.
How long does installation take? It depends on building size and how it fits with construction. First-fix must happen before ceilings close, so plan it into the construction schedule.