Thought leadership: Deciphering construction cost drivers for Indian grade A commercial space
Cost model: commercial
(grade A) office building
The building cost model is used to analyse project costs at an early stage and is based on historical cost trends and cost drivers.
Its objective is to provide an exhaustive breakdown of anticipated costs associated with constructing the fundamental elements of a project such as structure, exterior envelope, core services and finishes.
As the cost model assists with project budgeting and assessing the financial viability of prospective developments, it is crucial to consider regional construction costs, building regulations, design complexity and market conditions.
It is noted that costs for a campus-based development of commercial buildings for end-users would vary based on approach, design specification and requirements, as well as all add-ons included in the base build works.
The cost model is based on the expected range for a developer-led, multi-package, item-rate contract for a commercial, grade A, warm shell building/multi-tenant occupation. If the procurement strategy is altered, the cost model will have differential costs.
A general contractor with ownership of all work packages would have additional cost impact of 8% to 12% on the balance packages. In case of nomination (where risk of vendor performance is shared with the client), the additional cost impact would be 7% to 10% on the nominated package.
Basis of cost model:
- The office cost model is based on a prime location in a metropolitan city in India
- The building comprises three basements, a ground floor level and 10 typical floors. It has a built-up area of two million square feet
- Frame: RCC structure with PT slabs
- Building height is less than 70 metres
- Procurement strategies: trade package procurement and direct client procurement of high-end equipment
- Project contractor: grade A for shell and core works, remaining grade B
- Cost model is based on cost data available for March 2023
- The cost range is determined primarily by the site constraints, allowable areas and its interaction with the required structural solution, followed by overall specification levels and height.
Assumptions are based on the following considerations:
Civil and structure
- The cost of excavation is based on a combination of soft rock and hard rock strata. For piling or shore piling/diaphragm walls, additional costs vary from INR 80 to INR 120/sq ft
- Civil and structural costs are based on concrete consumption ratio of 0.048m3/sq ft and reinforcement steel of 5.5kg/sq ft. PT reinforcement is considered as per 0.4kg/sq ft
- For basement parking, driveway and ramps, VDF flooring has been considered (average 100mm thickness)
- External development is based on a combination of paver blocks, granite stone and landscaping elements with water bodies and vegetation.
Finishes
- Interior costs are based on INR 400/sq ft for Italian marble flooring in common areas such as entrance lobby and typical floor lift lobbies
- Granolithic flooring for all MEP and service areas.
Façade
- The façade is composed of 90% double-glazed, semi-unitised system and curtain wall for common areas, 5% stone surface and 5% louvres, doors and paintwork.
Services:
Electrical
- Transformer cost is 250W/sq ft with 80% diversity
- Generator rating is based on 70% overall connected load.
Plumbing
- Sewage treatment plant is based on SBR type determined by potential population based on National Building Code
- Organic waste convertor is based on local norm
- Water treatment plant is determined by potential population based on National Building Code
- Common toilets are based on INR 65/sq ft for vitrified tiles.
Firefighting
- Firefighting systems along with drencher, first fix fire hydrant in tenant areas and complete fire hydrant system in common areas. Fire curtains in parking areas.
HVAC
Standard air-cooled chillers cost is based on 350 sq ft/t in air-conditioned areas.
Mechanical carpark
- Mechanical stack parking as per parking requirements
- 8/10 ACH jet fan and exhaust systems
- Cost is dependent on type of parking system used e.g. puzzle/automatic/hydraulic.
Vertical transport
- Passenger elevators are based on traffic study with destination control system, standard 2m/s2 rate of acceleration. All elevators are of machine-room-less category
- Service elevators are based on 1 to 1.75m/s2 with group control technology.
Miscellaneous
- CCTV, IBMS system, IT system, parking management systems and security equipment based on standard common area requirements of grade A office space
- Solar PV panel system for 5% of the connected load for rooftop.
Source: Gleeds India internal database
The high-level cost range is shown in a graphical representation:
Source: Gleeds India internal database
