This is the final of three articles based around understanding more about how to achieve your Lift BREAM credits.
If you can satisfy the requirements of the first BREEAM lift credit you can then move on to the second. This article explains in more details ways to go about this.
The requirement is as follows:
Of the following energy efficient features, the three that offer the greatest potential energy savings are specified:
- The lifts operate in a stand-by mode during off-peak and idle periods. For example the power side of the controller and other auxiliary equipment such as lift car lighting and ventilation fan switch off when the lift is not in motion.
- Where lift motors use a drive controller capable of variable speed, variable voltage, variable frequency control of the drive motor.
- The lift has a regenerative unit so that energy generated by the lift (due to running up empty and down full) is returned back to the grid or used elsewhere on site.
- The lift car uses energy efficient lighting and display lighting (>60 Lumens/Watt or fittings that consume less than 5W e.g. LEDs
First things first
Specify them all, achieve maximum lift energy saving and be assured of a second lift BREEAM credit.
More and more lift manufacturers have these options available if not as standard and any associated cost premiums are reducing continually.
If you are considering an electric lift it is practically certain that the drive controller will be variable speed, variable-frequency, variable voltage – so this one is on the list of three almost by default. As a note, most of the energy used by lifts is used by driving them (60 to 80% typically) and these drives have 25% to 30% savings on energy, at least, in comparison with other drives. So this is almost certainly the biggest energy saver anyway.
The remaining three are dependent to varying degrees on quite a few variables and the lift energy saving calculations are not straightforward.
- Building Variables
- Lift travel
- Number of stops
- Lift variables
- Rated load
- Rated speed
- Suspension type (1:1, 2:1 etc)
- Traffic Variables
How much is the lift used; all the time, frequently, hardly at all?
And by how many people: one or two on each journey or more full?
Some broad examples
- Residential lift in small to medium size apartment block.
The lift is used in the mostly in the morning and evening and occasionally during the day. It sits idle for long periods.
Stand-by mode very significant
Regenerative drive of little significance
Low power display and lighting negligible as these can be timed to switch off after few minute of no lift use.
- Medium or large office building
Lift used throughout the day and intensely in morning, lunch time and evening peak
Regenerative drive can be very significant, especially for medium or large lifts
Stand-by mode little significance
Low power display and lighting more significant.
- Car Park lift in a Shopping Centre
Lift used steadily throughout the day but never intensely.
Regenerative drive fairly significant
Stand-by mode not that significant
Low power display and lighting more significant
How to calculate the energy use?
You will need to build up a model of the lift use profile starting with:
How many times a day the lift is running and for how long
What is the loading profile of the lift during that time
You can then use this base to go into more detail applying the other variables about the lift
Several manufacturers now have energy calculators for some of their ranges of lifts and based on the variables can provide a calculation of the energy consumption and potential savings for each of four Lift BREEAM credit criteria.
If this all beyond you and/or you are not of a mind to plough through the calculations, then one way of approaching the task is to ensure the Lift Specification is well written.
It definitely has to include the building variables.
It should also include practically all of the lift variables.
The traffic variables should also be included at least in terms of the anticipated operating hours, profile of use and maximum number of lift starts the equipment should be rated for.
That should be enough data for the lift company to calculate, with their equipment, the potential energy saving for each of the four BREEAM lift criteria.
You should ask them to provide this data as well as any associated cost premium and return it with their tender.