Automatic Fire Suppression System installations - traditional building conversion to hotels: cost benefit analysis

6. Analysis of Costs

6.1 Introduction

6.1.1 This section considers the costs of Installing AFSS into traditional buildings when being converted to hotels. The previous studies identified the main costs of installing sprinkler systems as:

• Installation costs including pipework, sprinkler heads, valves, power supplies.
• Water supply costs including pump and tank systems and connection costs.
• Annual maintenance costs/ongoing costs.

6.1.2 The previous studies did not relate to hotels or conversion of traditional buildings into hotels. As a result, discussions were held with four major companies who install AFSS to gather intelligence and costs to inform the analysis.

6.2 Consultations

6.2.1 A number of points were made during the discussion:

• Installation of AFSS in traditional buildings can be complex due to layout, ‘listing’ of parts of the buildings (e.g. ceilings) which must be preserved and require alternative approaches to installation e.g. access from the floor above rather than remove the ceiling. This can incur costs through additional time and labour requirements. It was estimated that this could add 10-15% to costs.
• Space for tanks and pump rooms can also be a problem in traditional buildings and can affect the viability of installing a system. With commercial systems, a substantial tank is required which could serve a relatively small number of rooms (e.g. 10) or a relatively large number of rooms e.g. >30. Contractor preference was always for the use of a pump and tank system as water pressure could not always be guaranteed by water companies.
• Consideration should also be given to other issues in traditional buildings which may impact costs. For example, is the loft space heated and if not, what frost protection may be required?
• BS 12845 is the standard for commercial sprinkler systems for hotels, although some smaller hotels have used BS 9251 systems for residential properties. Use of BS 9251 has a substantial impact on all aspects of costs.
• Water mist systems can be preferred in historic buildings as they use less water and have smaller pipes which can be beneficial where space is tight and there are artefacts to protect. However, the design and costing is more complex than with traditional sprinkler systems which tends to lead to higher costs. On average it was suggested that water mist systems could add between 30-40% to the cost of a sprinkler system.

6.3 Cost Estimates

6.3.1 Table 6.1 provides a summary of the information provided through the consultations. Costs were supplied on a ‘per installed head’ basis. As discussed above, there were many factors affecting the cost, but £300 per installed head was adopted as the average cost. This estimate will be used as the central case. The installed cost per head has been converted to a cost per square metre (sqm) by using the following assumptions:

• BS 12845: one head per 12 sqm (optimal use of space) and one head per 9 sqm (to allow for non-optimal use of space).
• BS 9251: one head per 25 sqm (optimal use of space) and one head per 19 sqm (to allow for non-optimal use of space).

6.3.2 Sensitivity analysis will consider a lower cost per installed head of £250 and will be converted to a sqm cost using the ratios which reflect the optimal use of space.

6.3.3 Water supply costs are substantial if a pump and tank system is required. The variation in cost in Table 6.1 reflects the larger size of tank required for commercial systems. As stated above, contractors recommend this system for water supply although reference was made to an example which did not have a dedicated pump and tank system. Sensitivity analysis will consider the implications of a mains fed system.

6.3.4 On-going maintenance costs are greater for commercial systems than residential systems as they require quarterly inspections and annual pump servicing. Residential systems require annual inspections and pumps are tested automatically.

6.3.5 The main focus of the analysis is the cost associated with BS 12845. The water mist systems are generally more expensive than BS 12845. Hence, if the benefit cost ratio for a standard sprinkler system is not favourable (costs exceed benefits) under BS 12845, the ratio will be even less favorable with a water mist system as the costs are greater.

6.3.6 To reflect potential variations in size of conversions of traditional buildings into hotels, three example projects were developed:

• A small 10 room hotel which can install a system under the residential standard (BS 9251) and is approximately 420 sqm.
• A small 20 room hotel with a commercial system (BS 12845) and is approximately 850 sqm.
• A larger 40 room hotel with a commercial system (BS 12845) and is approximately 1,700 sqm.

6.3.7 Table 6.2 provides a summary of the total cost of installing AFSS for the example projects listed above. The costs include installation and water supply and are shown for traditional buildings and non-traditional buildings. The main difference in costs between the building types is a 10% uplift on installation costs for traditional buildings.

6.3.8 The main point to note from the Table is the key difference in cost between the two system types e.g. residential and commercial. Although there is an uplift for traditional buildings to reflect additional time/labour costs, it is quite small as the majority of the installation cost relates to the pump and tank.

Notes:

1: includes installation and water supply costs