The unit method estimating consists of choosing a standard unit of accommodation and multiplying an approximate cost per unit. Estimate the building cost base on the depends on the population unit.
Unit Method Estimate = Standard units of accommodation x Cost/Unit
The unit cost method of estimation is used for project design estimates and bid estimates. The cost estimate is obtained by multiplying the number of accommodation for a new building with the cost per unit of accommodation based on a suitable building. The current unit of accommodation can be obtained by calculating from the sketch design or by obtaining information from the client.
For example:
- Schools – Costs per pupil place
- Hospitals – Costs per bed place
- Roads – Per Kilometers
- Car parks – Costs per car space
NGO will build a house for 1500 widows who are affected by natural disaster. Estimate the total cost to build houses. From a suitable cost data. The cost is $7500 for a house.
Total Cost = Standard units of accommodation x Cost/Unit
=1500×7500
=$11, 250, 000
The technique is based on the fact that there is usually some close relationship between the cost of a construction project and the number of functional units it accommodates. Functional units are those factors which express the intended use of the building better than any other. This method is extremely useful on occasions where the building’s client requires a preliminary estimate based on little more information than the basic units of accommodation.
The units adopted to facilitate this analysis depend on the type of project under consideration.
- Site condition
- Specification changes
- Market conditions
- Regional changes
- Inflation
Using unit method estimating method can generate a rough estimate quickly, but the lack of accuracy will render it of little use in the cost planning procedure outlined earlier. However, this method is often used to determine the very first notion of a price in early discussions of a project and as a crude means of comparing the known costs of different buildings.