By Anna Mårtensson, Erik Sävmark, and Matilda Bjälkefur
In some cases, sprinkler is a mandatory requirement in the local building code. But is there a way to find economic benefits from a sprinkler installation in a building where sprinkler is not a mandatory requirement? In this article we present a simple model that can be used in this matter.
The requirements for installation of automatic fire sprinkler vary in different parts of the world, which means that the way a sprinkler system can be taken into account in the fire safety design varies. In most cases there are however different types of buildings that don’t require sprinkler protection.
The use of fire sprinkler installations depend primary on four parameters:
- If an automatic fire sprinkler installation is a regulated demand in the building code.
- If automatic fire sprinkler can motivate lower demands on other aspects of the fire prevention which reduce the total costs.
- Demand from landlords or building constructors.
- Insurance companies.
As a basis for the example in this article the requirements in Sweden has been used, which is based on the Swedish building code BBR installation (Boverket, 2017). In contrary to many other countries Sweden only has a mandateory requirement for sprinkler in:
- Hospitals.
- Nursing and senior care.
However it is hard to design the fire safety in many other buildings without sprinkler (for example high rise buildings, indoor arenas and shopping malls), which makes sprinkler common in several other types of buildings.
If the building is equipped with an automatic fire sprinkler installation it is possible to reduce the demands on other aspects of the fire safety design. Examples of include:
- Allowing larger of fire compartments.
- Increased travel distance to escape routes.
- Reduced fire resistance of fire compartment walls and doors.
- Reduced fire resistance of structural members.
- More than two storeys in the same fire compartment.
- Less capacity of smoke control systems.
Against this background, sprinkler can provide an economical value, reduce the total building cost and increase the total leasable area while at the same time having the same or even better fire protection.
In order to determine whether it can be cost efficient to design a building when it is not a requirement for sprinkler Brandkonsulten AB have developed a model to analyse the cost benefits of a sprinkler installation.
The purpose of the model is primarily to be a decision making tool for property owners or general contractors when designing a building. The model is strictly monetary and do not consider the value of the risk reduction that the investment entails, such as the likelihood of total damage in the event of fire.
The model does not take any economic benefits into account that a possible insurance reduction may cause regarding to a sprinkler installation. Neither does it take into account the economic benefits that a sprinkler system may lead to in case of a fire, such as less mitigation nor less downtime costs. The model does not take into account the costs that may arise in case of water damage due to sprinkler malfunction. Neither does the model take other values into account, such as greater architectural freedom in material selection, etc.The model is based on fixed design of a building and comparison between a non-sprinklered and sprinklered option.
The Model
The model analysis the intended building by analyzing the fire safety features that are affected by the installation of an automatic fire sprinkler installation. Two alternatives of the building are set up and compared in the model;one equipped with sprinkler installation and one without sprinkler installation.
Before the analysis start the building must have a general fire safety design outlining the general requirements based on the given building layout without sprinkler protection. Thereafter, an initial fire technical investigation is performed for the building design alternative being protected by an automatic fire sprinkler system with the simplifications and reduced demands on other aspects of the fire protection that are possible.
When this is done, the cost of each the affected parts are calculated. For the building alternative without a sprinkler installation, additional costs are stated for each item that can be reduced for the building provided with automatic fire sprinkler. For the building alternative provided with a sprinkler system, the additional cost for the sprinkler installation is stated. For example, if the building provided with a sprinkler installation can be designed with reduced fire resistance for the fire compartment walls. The additional costs for the fire compartment wall are calculated for the building without a sprinkler installation.
In addition to the cost of production in the construction phase the cost of non-leasable area is also taken into consideration. For example, if the building provided with a sprinkler installation can allow for longer travel distances to escape routes there could be a situation where less escape stairways are required, additional cost of the non-leasable area is stated in the non-sprinklered option. The additional cost in this model is calculated over a chosen period of time and discounted to a present value.
The last item included in the model is the cost of operation and maintenance, such as operation and maintenance of sprinklers and smoke dampers. This item is also discounted over a given time frame, for example 10 years.
This is shown in a table that describes the various parameters that are affected by the fire sprinkler installation, as shown in figure 3. The costs are separately to make it easy to enable decision making when the direct installation costs are the primary aspect. Another reason is that the initial costs are different from the loss of revenue. In the model, it is assumed that all the leasable area is fully rented throughout the selected time period.
In order to determine costs for each item, a building cost estimator should be consulted. Since prices are directly determinative to the outcome of the model, it is crucial that they are correct. To get a good overview of the costs, it may be necessary to include project-specific costs for certain products in order to get a good price indication. Prices must also be adjusted for local conditions in each case, for example, what the leasable space is worth in the current geographic area.
Figure 1: shows a flow chart of the different steps of the model.
Figure 1. Flow chart of the different steps of the model.
Example Building
To show how the model is used an example from a real project is used. In the example studied following easements on other aspects of the fire protection have been assessed as possible and relevant when installing a sprinkler system:
- Fewer fire compartment walls.
- Lower fire rating of glass in the fire compartment wall (to the atrium).
- Reduction of number of stairwells, from 3 to 2.
The automatic fire sprinkler installation may also, in a more detailed analysis, show other alternative design options. However, at an early stage, the most cost-effective simplifications are the most interesting.
In this example the building is located in a popular area in Sweden with a high rent per square meter.
Figure 2: Example building, layout.
The results of the example are shown in figure 3.
Figure 3: The results of the example.
Can There Be Economic Benefits from a Sprinkler Installation?
In the example above the model shows that there can be major financial benefits in installing an automatic fire sprinkler system in a building. In geographic areas where prices for leasable floor units are higher per square meter, it is more beneficial to install an automatic fire sprinkler system if it can create more leasable area, for example by removing a stairwell. On the other hand, in areas where the price for leasable floor it can be of interest to reduce the construction costs, for example by reducing the fire rating of glass, increasing size of the fire compartments (i.e. fewer fire compartment walls, fewer doors with fire rating classification and fewer smoke dampers).
Determination of cost is important to get right. It is therefore important to include a building cost estimator in each analysis. Analysis made on rough estimations of costs or old prices may give an incorrect result of the analysis.
Hopefully, this model can be a useful a tool and basis to assist decision-making for property owners and building contractors in when deciding if the building should be provided with an automatic sprinkler system or not.
Anna Mårtensson, Erik Sävmark, and Matilda Bjälkefur are with Brandkonsulten AB, Sweden
Reference
Boverket. (2017). BFS 2017:5. Boverkets byggregler.