Lifts* are being specified in Passive House residential buildings—installed straight away or space is being allocated to allow for installation when needed later. Universal accessibility is a very sensible idea, especially in the context of an ageing population and the growing wish to age-in-place, plus the need for increasing urban density by building up. We expect to see lifts appear more and more, as multi-unit residences and non-residential Passive House projects increase. In this article, our advice is tailored to single family homes.
Lift energy use isn’t that hard to calculate in PHPP but there are a few things Passive House designers need to get their heads around. The very short summary about lifts and PHPP is:
- TFA—out
- Volume—in
- PER—in.
PHI has made a tool to make calculating lifts easier. Second, if you are measuring the power use, the standby power has much more of an impact than the energy consumption during use. If the lift will be installed at the time for construction, the following rules apply. The lift footprint is excluded from TFA on all levels and the lift shaft volume (right through the midfloor) is included for blower door test volume. The lift energy use must also be included for the PER calculation (renewable Primary Energy Demand). Here’s PHI’s lift tool that will help determine the energy use of the lift.
However, if the building has only a future allowance for a lift—a storage cupboard that can be converted into a lift shaft—then you get a free pass basically. The design does not need to factor in the lift for certification purposes. Provided the cupboard has a finished floor, simply follow regular TFA and volume rules.
Here’s an example of a completed worksheet for the lift tool:
Fig 1 PHI Lift energy demand tool, completed
Is there an energy label available for the specified lift? Great! Simply enter it in the first drop down field: in the example above, it’s an A-grade lift.
If an energy label is not available, there are two choices. One, make a conservative assumption—for a domestic platform lift, B-grade is a safe choice. Alternatively, measure the actual standby demand. In a residential setting, standby demand is what matters in terms of PER as the time of actual usage is so small. In the example above, standby energy accounts for fully 98% of the lift’s total energy consumption. It only really becomes critical if a project is targeting Passive House Plus or Premium certification and there’s little margin for the PER target.
Here are completed entries of the data that needs to be included in PHPP.
*known as an elevator in other parts of the world!