Are our city economies overheating?

High demand for new developments is taxing the minds of consultants and contractors, says Geoffrey Palmer

As consulting engineers, we all ponder overheating, the urban heat-island effect, cost-effective CO2 reduction and the overall sustainability of our projects. We use BIM, passive design, complex analysis, soft landings and a myriad of other tools to better understand our built environment, and the part it plays in wider society.

Overheating and recent climate change of a different sort, however, is also taxing the minds of consultants and contractors. I am referring to the London speculative development market. Never before have we seen so many instant flat sales, off-plan to overseas and wealthy investors. This demand has resulted in a massive increase in this area of the market, one with which designers and builders are struggling to keep pace. Recruitment of good individuals – rather than just the traditional concern of work winning – is taxing many in our industry. Not a bad thing, I hear you say, but is this sustainable? How do we keep diversity in our business to cushion any future slowdowns? How do we generate robust designs that a rapidly growing contractor workforce can implement when skilled labour becomes a rare commodity. Repetition, off-site fabrication, multiskilled operatives and more extensive use of modern systems and techniques must have a part to play.

Let’s start with repetition. This allows installation teams to develop their ability through a project, maximise the use of apprentices and help build growing capacity as more work faces become available on a project. A good level of repetition also opens additional avenues for modularisation and off-site fabrication. When we do get high repetition and a great desire to hand over completed sections of large projects – where connections to prefabricated elements are necessary – there may be benefits from multiskilled teams, again with apprentices growing into the role.

New developments in Salford, Manchester

Large projects have always warranted off-site discussions, with many electing to use toilet pods, some incorporating riser modules, and a few on-floor services and large-scale plantrooms. Now it is capacity, as well as installation speed and quality, that is a key driver in these discussions. Off-site fabrication is often talked of, but we need to change this term to design for off-site fabrication. This ethos cannot be bolted on but must run through the whole design process from day one. Otherwise opportunities for off-site fabrication will be to zero.

So what are the modern systems I have alluded to? Modern may not be the best term, as many of these technologies have been available for some time. From pre-insulated ductwork to self-balancing controls; from plug-and-play lighting and modular wiring systems to proprietary jointing. These exist to make site work and testing easier. Such systems are often discounted on cost grounds, but – in this new climate – engineers need to consider them more fully and help ensure their pricing and cost-benefit analysis are robust. This is at a time when rapid market growth can make effective cost estimation more difficult.

Another area for consideration is the real-life diversity in some of our most expensive residential towers and whether our designs have been optimised for the potential part-load and part-occupied scenarios. We have seasonal efficiency data for key building plant, but our regulations generally assume full in-use buildings. While total energy use may be below that calculated for building control, without careful consideration of controls strategy and part-load performance, relative efficiencies can quickly drop off.  As engineers, we often look at this type of analysis, but how often does the ‘what if’ scenario have a real impact on plant selection?

In my business, I have looked at regional diversification to provide some additional robustness and new sector penetration alongside the speculative London market. We now have a good presence in Manchester and are undertaking some large industrial projects, although recruitment of good people here remains challenging.

I may be worried unduly about these additional technical challenges and having lots of eggs in one basket, but I can’t be the only one. Can I?

Geoffrey Palmer FCIBSE is a director at Grontmij, part of Sweco