IES-VE User Forum

From the NCM activity database available from uk-NCM.org.uk the hot water usage of a hotel ensuite room and a hotel changing room is 6.4 l/m2/day and 30 l/m2/day respectively.

However, in the room conditions tab of tabular room data in IES VE compliance the hot water usage of the hotel ensuite room and a hotel changing room are given as 13.55 l/h.person and 83.997 l/h.person respectively. When the room occupancy (10.59 m2/person for ensuite and 8.4 m2/person for changing) and is applied to the hourly occupancy profile (10.25 hours per day for ensuite and 12 hours for changing) this comes to 13.199 l/m2.day for the hotel ensuite room and 199.995 l/m2.day for the hotel changing room. Quite different to the NCM activity database above!

Can anyone offer an explanation for this?

The value in the NCM Database is static for the entire year, and when used by SBEM, the only variation in the calculation is the days in the month. So over the year Hot Water Consumption is uniform for months containing 30, 31 days etc...

Instead of SBEM's one calculation per month, DSM's are able carry out over a hundred calculations for each day in the year, so they can more accurately simulate hour to hour consumption of Hot Water over the period of the simulation. To do this under the regulations though, they have to follow occupancy schedules (See paragraph 56 from the 2013 NCM Modelling Guide.), and also use a factor from the UK NCM database for average occupied hours per day (shown as HWS_HP_FACTOR) when determining the DHW consumption rate (i.e the value displayed in the VE in Room Conditions). I think this factor will be where you've gone wrong...

Software displays DHW Consumption Rate = 83.996 l/(h.pers)

Using the following the UK NCM Database

Hotel changing HWS Consumption: 30 l/day/m2
Hotel changing occupancy = 0.119052632 person/m2
Hotel changing average occupied hours per day = 3
Conversion from litres/day/m2 to litres/hr/person: 30 / (0.119052632 * 3) = 83.996 - which matches the displayed value in the VE.