Measures to Address Durability Issues When Wind-swept Rain Enters Lift Shafts of HDB Blocks

11 Dr Tan Wu Meng asked the Minister for National Development (a) whether the designs of new HDB precincts have taken into account the variability and range of inclement weather, including heavy rain and strong winds; (b) whether the assessments have considered the prospects and implications of wind-swept rain entering lift shafts and affecting lift equipment; and (c) what rectification measures have been considered by HDB for new precincts where wind-swept rain has raised concerns about lift durability.

The Second Minister for National Development (Ms Indranee Rajah): Mr Speaker, in Singapore's tropical climate, strong winds may cause rainwater during a heavy downpour to enter common property that is not completely enclosed. The Housing and Development Board (HDB) has employed various design strategies over the years to try to mitigate the extent of rainwater splashing into homes and common areas.

These considerations are incorporated into HDB's design requirements, to ensure that our precincts are reasonably well protected from the tropical weather even as we design for natural ventilation and ample lighting. In view of increasingly volatile weather patterns brought about by climate change, HDB has conducted wind-driven rain, or WDR, simulations for all new public housing developments since 2021.

Through the WDR simulations, the effects of rain and wind, even in more extreme conditions, are modelled to identify areas prone to rainwater splashing. This allows designers to implement mitigating measures early during the design stage.

HDB adopts design features recommended under Building and construction Authority's (BCA's) SS 550-2020 standards for lifts, such as sloped thresholds at lift doors to reduce the risk of water ingress into the lifts. HDB also installs rain screens and canopies at the lift lobby, if these are found to be necessary. These measures are generally adequate to keep rainwater out of the lift area.

Mr Speaker: Dr Tan Wu Meng.

Dr Tan Wu Meng (Jurong): Mr Speaker, I thank the Minister for her answer. I have been approached by residents in Clementi Peaks, a very new precinct in Clementi. My residents share that about one year after they moved in, HDB started installing rain shields at lift lobbies which blocked their view of the beautiful Clementi scenery.

We are told that the reason was to prevent rain entering the lift shafts, which would affect lift reliability and corrode the lifts. My supplementary questions are, firstly, does the Minister not agree that heavy rain and strong winds are not unknown in the West of Singapore, including in Clementi?

Secondly, can I also ask the Minister – hindsight is of course 20/20 – but in hindsight, could HDB have done an even deeper study into the climate situation in the west of Singapore before the development was being built? And if there was a discovery of rain entering lift shafts during the construction phase, whether these rain shields could have been installed earlier and incorporated into the design earlier?

Lastly, Mr Speaker, we know safety is important, especially lift safety, and if there is no other option, safety must come first. But can the Minister assure us that HDB will learn from each new development, including Clementi Peaks, so that future developments will be even better and consider climate change even more closely.

Ms Indranee Rajah: Mr Speaker, I thank the Member for his supplementary questions. I think he had three. The first one, he asked whether it would be possible to anticipate that there are heavy rains and strong winds, including in the Clementi area.

The answer is yes, and that is the reason why HDB has included the modelling of WDR simulations for new public housing. But in the particular case that he raised, which is I believe the case of Clementi Peaks, maybe I should explain what happened here. Before I do, let me just talk a little bit about the WDR simulations.

They are computational fluid dynamics, or CFD, for WDR simulations and they are conducted to meet the following HDB requirements: to identify and prevent rainwater from splashing to residential unit entrance gate and lift doors; to identify and minimise rainwater splashing to sheltered accessible routes, including drop-off porches, link bridges and linkways or void decks; and to demonstrate the effectiveness of mitigation measures proposed, such as modifying the corridor layout and/or design mitigation measures up front that will match the façade and meet the fire safety requirement.

In the case of Clementi Peaks, however, Clementi Peaks was completed in October 2022 and this means that the design was finalised before HDB began incorporating the CFD simulations for WDR, which was in 2021. And shortly after handover, the residents reported that there were issues of rainwater splashing into the common corridors and lift lobbies on the higher floors, and this posed a risk of seepage into the lift shafts. HDB then decided to install additional rain screens at the lift lobbies to protect the lift, as a key infrastructure in common property, from rain splashing and this was for safety reasons and to avoid disruption of lift operations, which would, of course, affect all residents.

And therefore, after consultations with HDB and the consultant, the contractor then served notice to residents of the installation of the rain screens at the affected lift lobbies in mid-August of 2024.

The first point I want to make is that for Clementi Peaks specifically, that was before the WDR simulations were put into effect. The second point I want to make is that the works that were done were primarily for safety reason. The third point I want to make, and this acknowledges what the Member brought up, which is that I think the learning lesson from this is that it is helpful to engage the residents earlier, to let them know the reason why the installation is being done, and also possibly to take feedback, because in this case, as I understand it, residents were concerned about the view being blocked.

In short, I think we would improve the engagement process where issues like these arise in future.