Traditional building conversions - Automatic Fire Suppression System installation: additional sensitivity analysis

Introduction

In response to the consultation, the British Automatic Fire Sprinkler Association (BAFSA) and European Fire Sprinkler Network expressed concern about the cost benefit analysis (CBA) on two main points:

1. Damage costs: The damage costs in the CBA were based on the average cost of constructing a mid-range hotel. Views were expressed that the cost per square metre for a mid-range hotel was too low as conversion of traditional buildings are more likely to be to ‘upmarket’ hotels.

2. Water supply: The water supply costs under the EN 12845 scenarios were felt to be too high for hotels of 20-40 rooms as hotels of these sizes would be able to have reduced water and pump capacity.

Following a discussion with BAFSA and the European Fire Sprinkler Network, it was agreed that some sensitivity tests would be undertaken to address these concerns. The sensitivity analysis is only focused on traditional hotels and the scenarios which relate to BS 12845.

Additional Damage Cost Sensitivities

The CBA damage cost was based on a cost of £2,810/sqm for a mid range hotel with leisure and conference facilities. Two alternative, higher costs are available:

a. £3,900/sqm for a business city centre hotel with conference and leisure facilities.

b. £5,350/sqm for a luxury city centre hotel with conference and leisure and facilities.

Sensitivities a) and b) have been run with the original costs and these revised damage costs. The results are shown in Table 1.

Additional Water Supply Cost Sensitivities

The water supply costs in the CBA under BS 12845 were substantial at £185,000. These related to supply under OH3. BAFSA agreed to approach some members to ascertain costs relating to water supply costs under OH1, which they felt would be more appropriate for 20-40 room hotels.

Information was requested for the following water supply systems:

i. OH1: 1x reduced capacity tank 10m3 and 1x half capacity tank 27.5m3.

ii. OH1: 2x 27.5m3 half capacity tanks.

iii. OH3: full capacity (2x 67.5m3 half capacity tanks).

The information request assumed that the height would be less than 15m, there would be one diesel and one electric pump, electrics are excluded as they would be provided by others and there would be no new plant room required (i.e. existing space would house the pump and tanks).

The information provided showed that there was not much difference in cost between options i) and ii) above – less than £5,000. The information for option iii) confirmed that water supply costs under BS 12845 OH3 are substantial and the latest cost was slightly^[1] higher than the £185,000 assumed in the CBA.

In light of the new information, one additional water supply sensitivity has been undertaken:

c. Cost of water supply reduced to £155,000^[2] to reflect installation under OH1 with reduced capacity and half capacity tanks (i) above).

The results are also shown in Table 1.

Combined Sensitivities – Damage Costs and Water Supply

The final two sensitivities combine the higher damage costs with the lower water supply cost for OH1 as follows:

d. Based on business hotel construction costs and reduced water supply.

e. Based on luxury hotel construction costs and reduced water supply.

The results are also shown in Table 1.

Results

Note: All scenarios include an additional uplift to wider damage costs

When the construction costs of a luxury hotel are adopted, the BCR is one or very close to one (sensitivities b) and e)).

When the construction costs of a business hotel (sensitivities a) and d)) and a mid-range hotel (sensitivity c)) are adopted, the BCRs remain below one.