20-0408 v4.0 Potable Water Reduction Target

Question

Our project consists of the conversion of 2 existing warehouses into an office space. One of the warehouses will be taken down and rebuild and it will have total of 250 workers. The other warehouse will keep its structure but systems will be renewed and it will have 750 workers. Since in both cases plumbing systems will be renewed, will the target of 50% apply to the project, even when one of the buildings is existing ? Further, to understand our target, table 5-1 in the petal handbook indicates we can consume 40,15 liter of potable water per person per working (?) day without considering irrigation. Since we have 249 working days, our baseline for potable water consumption would be 9.997.350 liter. The uses we will have in the building are the following: kitchen sinks, showers, bathroom sinks, dishwashers and toilet flushing. We will not have drinking water fountains, clothes washers, cooling towers or urinals. Is the baseline of 40,15 liter the same for all office projects even if they have other uses such as cooling towers and/or water fountains? Or do we have to reduce the baseline to take into account the uses we do not have in our project? Please confirm our target would be 0,5 x 9.997.350 liter = 4.998.675 liter per year considering we will have 1000 workers.

Answer

Because the plumbing systems are new, the required use reduction is 50% from baseline.
The calculations for baseline and target annual consumption in the post are correct. 
With respect to the cooling tower, we understand that this project is connected to a district heating and cooling system that uses water in combination with a chiller to produce cooling (a strategy covered under the term cooling tower), but that the water used is non-potable seawater. The LBC 4.0 baseline for offices does include water used for cooling and heating (broadly). The team should thus use the office baseline, but because the cooling system that serves the project uses non-potable water, that water does not need to be accounted for in the required reduction in potable consumption. However, if there is any potable water used in the district heating and cooling system, because the project benefits from that use, a portion of the volume needs to be assigned to the project, and counted in its potable water consumption. The apportioning can be done by calculating the area of the project relative to the total area served by the system and applying that % to the project. 
The other uses the team references are not explicitly included in the LBC 4.0 office volume baseline and do not need to be deducted from the baseline.

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