Improved calculation models give environmental guidance to urban development projects 

2019.08.13 / Marie Haeger-Eugensson

With climate change and urbanisation, factors relating to wind speed, temperature, air quality and noise are growing more important when planning new suburbs, industries and buildings. Fortunately, the models to calculate these factors are evolving all the time to the benefit of both environment and budgets.

It used to be that an urban developer might only discover that an environment was too noisy or windy, when the construction was already under way, and then it was too late. Today, assessments of air, noise and climate’, are often involved at an early stage in a project, and as the calculation models develop, the knowledge becomes more usable.

With the help of advanced 3D calculation models, we can come in at the early planning and design stage and show that an area will be exposed to high levels of pollutants. Where this happens, changes can be proposed, thereby preventing late stoppages and/or rework of construction processes driving up costs.

One type of measure could be to build higher. We know that high buildings produce higher wind speeds at ground level, which can help to blow pollutants away. Another approach that can be used is vegetation, where we often collaborate with the landscape architects.

High impact from noise and air pollution

Impact of noise and air pollution on existing or future buildings or infrastructure projects increases the need for investigations.

In cities like Gothenburg and Stockholm in Sweden, many of the new construction projects take place in areas that were not previously exploited for various reasons. Here there is often a big impact from both noise and air pollution, which is why the need for this type of study has increased and has to be taken into account in urban planning.

In the construction of the West Link in Gothenburg and East Link outside Stockholm in Sweden, for example, both air quality (particles and dust formation) and noise need to be investigated. To know when these need to be looked at, we have run an R&D project and produced guidelines on behalf of the Swedish Transport Administration in order to offer recommendations – such as stopping any kind of construction work in some weather conditions so as not to raise particle levels too much.

Climate changes effect construction industry 

In terms of future change, we have known for a while that we can expect more extreme weather, which means more periods with high water levels, and longer and more extreme spells of both heat and cold. Changes in water levels have been discussed for many years, probably because they have big direct effects on societal functions and entail large direct costs. More frequent hot periods have been shown to affect human health, with more deaths and more people admitted to hospital.

An altered urban environment in the form of very high buildings or dense development risks affecting the temperature in the city even more.

As we are now making such major structural alterations to our urban areas, we have a fantastic opportunity, through well-thought-out urban planning, to take account of the effect of development on the local climate, the effect of the future climate, and ways to ensure that noise and air quality are not made worse.

A warmer climate will also require the construction industry to take these new findings on board, as this is likely to affect the scale of future cooling/heating needs, and hence how buildings are designed.

The future spread of electric cars will also bring changed assumptions. NOx emissions from road vehicles will be much lower and, in the best case, drop to zero, but no equivalent reduction in particle levels is being forecast at this time. In Gothenburg, for example, 70 percent of the particles in the atmosphere are estimated to come from tyre wear on the road surface, whipped up into the air.

New guidelines for how to model in an urban environment 

Crucial issues in future urban planning are likely to be: What requirements will need to be included as we plan our cities in the future? How can we best handle the effects of climate change? And which factors will come into play as we change our ways of moving around?

Fortunately, we are seeing improvements to environmental modelling work in various areas. In 2019, for example, the Swedish Environmental Protection Agency will present guidelines for modelling in an urban environment, which I have produced at Gothenburg University in collaboration with the Swedish Meteorological and Hydrological Institute (SMHI).