There are some people who are saying that the excessive rain is not related to Climate Change. To argue this isn’t of concern at this particular moment – the reality is that the rain did come down and there is no evidence that it will not happen again so it is sensible to update our thinking of possible scenarios and act accordingly. Recently I have been culling my architectural library, as I have recorded before in these blogs, and I continue to come across articles from the mainstream building industry press of the early 1980s discussing and warning of the coming Climate Change and the need for action at all levels. I find it interesting that there was a falling off of writing as the eighties progressed, and on through the nineties, as the climate deniers gained a foothold. The world has lost forty years of opportunity to make an ordered and timely transition. It is never too late to start; just much more expensive and difficult.

What can the Politicians and Built Environment Professionals, and the wider society also, do to address the rapidly developing and apparently overwhelming effects of Climate Change? What we each should not do is stand back because we consider that our individual effort would be too puny to have any effect.

As the Anglo-Irish Philosopher Edmund Burke {1729-1797} said; “Nobody made a greater mistake than he [they] who did nothing because he [they] could do only a little.”.

Even so, we can but try. As professionals, within our design work there are many small things which can be done at little cost but which would be effective throughout the life of the property.

The late January 2023 Auckland floods were a disaster for housing which were confidently assumed, or legally argued, to be secure from damage. In the North Shore’s Wairau Valley the commercial area suffered substantial flooding damage from adjacent overflowing waterways and drainage infrastructure inundating the ground and basement floors of the low-lying premises. Some commentators, after the event, spoke of making the city ‘spongy’, ie., making the environment able to soak-up the excess water as it falls. This is already being done through the requirement for water storage and detention tanks plus permeable landscaping, etc., and some owners are going further by incorporating swales on their properties. These are perfectly sensible design solutions to moderate the peak water flows into the public stormwater system during rain storms. I understand the Wairau Valley development has a ‘detention lake’ which serves the same purpose.

These work fine for normal rainfall but, given the long life of this infrastructure investment, is it sensible to be designing to the minimum capacities of today? As anyone who has washed the car knows, sponges become saturated and the excess water has to be wrung out before continuing. With these stormwater retention methods a point is reached where the inflows exceed the outflows, and so the detention aspect is lost, and therefore the system acts as if there is no detention capacity.

In the case of the Wairau Road commercial premises, I was not aware of any reports of water entry from the roof and guttering despite the “train of thunderstorms” passing overhead. When I was a student in Auckland there was an occasion when a thunderstorm occurred which caused flooding havoc to large commercial buildings. Ever since, this event has influenced my design of internal gutters, no matter how small or large the area of the building’s roof. In addition to the usual downpipes connected to the stormwater drains, or a rainwater head, I always include an adjacent weir overflow. This is open to the sky rather than being the usual tidy, adequately sized, overflow penetration through the façade.

The reason for this design philosophy is that the thunderstorm was actually a hailstorm and the hailstones blocked the outlets causing the water in any gutter without an adequate overflow to rise above the lateral freeboard and so flood into the interior. Soon afterwards there would have been no evidence of any cause because it had melted away. The cause is very simple physics – ice floats and sticks together when pieces are brought together. The hailstones are carried along on the water flow to the downpipe where they quickly form a plug to effectively seal the outlet. By having a topless weir overflow the icebergs are, without hindrance, washed over the lip by the rising water. A simple device which will usually prevent or minimise very substantial water damage from a 15 minute hailstorm.

After the Cyclone Gabrielle floods there were stories of people climbing on furniture; going to an upper storey; and then as the water rose higher climbing into the roof space – sensible in the logic of emergency decision-making as it would be raining outside – but very dangerous if the water should rise further. In former times concrete tiles would allow easy access to the exterior should that become necessary, and they have the added benefit of tile battens as foot and handholds. Applying some design thought, it seem to me there is a simple safety measure that could be easily incorporated into the roof construction of dwellings on known floodplains. This is to fit an access hatch, preferably glazed, sufficient to allow egress in an emergency. A few permanent roof anchors could be strategically placed close by. An immediate objection is that it would be an expense very unlikely to be needed and would never be used. This is valid but boating lifejackets have the same characteristics; virtually all lifejackets are never used for the purpose for which they were designed.

A (wired glass) glazed roof egress hatch would not need to be as redundant as might be expected. The house’s thermal envelope is at ceiling level so there is no heat loss, it would provide adequate light to find the suitcases, and for dwellings with ventilation equipment in the attic additional light for when the filters are occasionally changed. Of course measures would need to be taken to prevent the kids from using the route to play games on the roof. No burglar is going to climb onto the roof, where the neighbours can observe the break in, when there will be a window hidden around the back for a much easier entry.

Needing to cope with unexpected events, and exploring potential design tweaks in advance, no matter how small, can generate significant changes in how we handle and accept the inevitable climate changes that are already upon us. In previous blogs I have raised questions and points for discussion on sustainability matters which may be of interest to the reader.