It is a simple calculation to compare the energy consumption of an installation using conventional fume cupboards and an installation utilising Premier’s new Enterprise DynamicFlow fume cupboards. The following calculations are based on a typical installation employing thirty 2m wide fume cupboards.
The volume of air consumed by a conventional fume cupboard is a constant figure calculated by:- Sash open width (m) x sash open height (m) x face velocity (m/sec). So for a 2m wide cupboard:- 1.7 (m) x 0.5 (m) x 0.5 (M/sec) = 0.425 m3/sec.
The total extract volume from a laboratory equipped with thirty conventional fume cupboards would therefore be:- 30 x 0.425 m3/sec = 12.75 m3/sec (45,900 m3/hour).
This volume of air will be replaced by the supply air system plus a small quantity of air drawn from adjacent areas to maintain a negative pressure within the laboratory. This air would be heated/cooled from the ambient air temperature to the desired laboratory air temperature (typically 21°C).
Assuming an average day time temperature for the UK of 9°C over the whole year, the average energy consumption per hour is given by the formula:- Volume (m3/sec) x temperature rise (t°C) x 1.21 (constant for air)
In this case:- Average Consumption = 12.75 m3/sec x 12°C x 1.21 = 185 kW (per hour) Assuming a fume cupboard usage of 8hrs/day, 5 days/week and 48 weeks/year, the average annual energy consumption for a conventional fume cupboard would be:- Annual Consumption = 185kW x 8 hrs/day x 5 days/week x 48 weeks/yr = 355,200 kWh/yr.
As the Enterprise DynamicFlow fume cupboard operates on a face velocity of 0.25 m/sec as opposed to 0.5 m/sec the required volume is 50% lower than the equivalent conventional fume cupboard.
Therefore: Average Energy Consumption = 355,200 x 0.5 = 177,600 kWh/yr
The above figures are given as a guide to the potential energy savings when utilising Enterprise DynamicFlow instead of conventional fume cupboards.
The calculations do not include for any cooling requirements which can be calculated using a similar method.
The typical cost per kWh used in the UK is £0.10 and is based on a combination of direct fuel costs, plant maintenance, and depreciation of plant, ie a true cost of energy.
Applied to the examples above, the total running cost for a ‘conventional’ versus an Enterprise DynamicFlow installation can be stated in general terms as follows: