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Early data details help rigorous design

Justin Nicholls

Tools like digital twins of cities that add a layer of microclimate data to 3D conceptual designs can bring sustainability deep – and early – into architects’ work

The construction industry contributes to a colossal 39% (WorldGBC) of the world’s carbon emissions and architects have a pivotal role to play in reducing this. In recent years engineers have led the way in good quality data modelling of building performance, but as these complex models are time consuming they tend to be run late in the process. The design is typically conceived much earlier using the skills and intuition of the design team. At Fathom we’ve been testing digital tools that can bring more rigour to the conceptual stages and follow this with close collaboration to ensure the engineering model is at the heart of decision making.

Detailed 3D models of design proposals have been around for some time, and ViewCity’s London model – a fast evolving digital twin of our capital –is now providing us with accurate, data-driven context within which to design. As well as massing and visual impact, the model overlays data on microclimate including sunlight and overshadowing. This early information helps us make informed decisions about aspects like location of entrances and terraces before the concept design is fixed.

More upskilling and investment of time is needed to combine transport and pedestrian metrics with air pollution and noise data.

Perhaps unexpectedly the south facing, tree shaded, ground floor living room overheated more than the dual aspect south and west facing bedroom

Following initial design studies, we get more detailed. One of our architects has been using Grasshopper scripting skills to create a precise heat-map on the facade of sunlight exposure throughout the year. With graphic clarity, we’re able to spot counter-intuitive outcomes, especially with projects in the narrow and winding streets of a UK city. We then sketch, model and rerun until we have developed a coherent architectural language which also does the dutiful job of tempering the environment.

Despite our considered early efforts, it’s the engineer’s model that has authority. It forms the basis of the carbon calculations for planning, cooling and heating loads, equipment sizes etc. Careful collaboration is needed here. We work hard to give those modelling more airtime to ensure inputs and assumptions are correct. For example, in a home a typical model assumption is that internal walls are plasterboard and floors are timber. Interrogating this model, we found that switching to stone floor and brick walls reduced peak overheating by more than 50%, allowing us to bring forward design and client decision on finishes.

It’s also important to integrate the outputs – perhaps unexpectedly the south facing, tree shaded, ground floor living room overheated more than the dual aspect south and west facing bedroom. We discovered that occupants don’t like leaving ground floor living room windows open at night so the space doesn’t get purged – we would never have known that had we not been rigorously questioning.  

At Fathom we’re excited that intuitive digital twins, such as ViewCity, and innovative software learnt in academia like Grasshopper, can be brought into practice to add rigour to our processes and thinking. We’re also not forgetting the importance of person-to-person collaboration – continued knowledge-sharing is essential to a productive detailed iterative process of design evolution. Our commitment to depth of thinking highlights that the first answer is rarely the right one. 

Justin Nicholls is director at Fathom Architects



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