Dr Ryan Southall researches the environmental impact and performance of buildings, developing tools, techniques and processes to make buildings more energy efficient. He’s worked in the field for twenty-five years, beginning with research into energy efficient windows. His current research and development focuses on low-energy forms of ventilation and analysis of whole-life carbon in buildings.

Analysing the carbon footprint of buildings

‘When we talk about whole-life carbon in buildings, we’re looking at the two carbon consequences of a building,’ explains Dr Southall. ‘These comprise the operational energy (or carbon) such as heating, lighting, air conditioning and so on, alongside embodied carbon, which is the carbon emissions associated with the materials, and their transportation, required for the construction of the building, the maintenance of it and eventually, the demolition of it. The analysis of the carbon emissions associated with these two things together is what makes up the whole-life carbon of a building.’

Much of Dr Southall’s current research activities revolve around the VI-Suite software. VI-Suite, authored by Dr Southall, is an interface for a set of analysis tools that enable the measurement of environmental performance. He designed VI-Suite in order to try and make up for some of the shortfalls in existing software relating to performance analysis of buildings.

‘VI-Suite is an intermediary and easy-to-use interface that enables existing open-source software tools such as Blender (for geometry and material specification), Radiance (for lighting simulation) and EnergyPlus (for building energy performance simulation) to be used together,’ says Dr Southall. ‘In this way, the geometry and physical construction of a building can be easily created as a virtual facsimile, and the results visualised clearly by the analyst or architect.

The evolution of ventilation

‘One of the ways I’m using VI-Suite at the moment is for my work in developing more effective and environmentally efficient ventilation systems. The UK has traditionally had a fairly basic relationship with the ventilation of buildings, owing to our mild weather. Historically, it was just a system of fireplaces for warmth, while the small cracks, crannies and crevices within the building fabric allowed air in and out. Then, as 20th century houses started to be built with more airtight construction, specific ventilation began to be introduced – primarily via the use of a trickle vents, which is a narrow slot above a window that can be opened and closed manually. The downside of trickle vents is that they are affected by wind – on a cold, windy day, more outside air will enter, cooling the room. When this happens, people often close the vent and forget to re-open it later.

‘In addition to the trickle vent, mechanical forms of ventilation were also introduced, such as extractor fans, which might be constant or intermittent (such as those activated by switching on a light in a bathroom).

‘At the moment the current UK standard for low-energy ventilation is MVHR – Mechanical Ventilation with Heat Recovery. MVHR brings fresh filtered air into a building whilst retaining most of the energy that has already been used for heating. However, this system has disadvantages because it requires an airtight house and needs maintenance. There are running costs too – for energy used to operate it, as well as maintenance. Problems associated with poor installation and operation have also been widely reported.

‘With this in mind, I’ve been developing a new ventilation system that is a throwback to the trickle vent, but with technical innovation to override the shortcomings of the original system. This new type of vent has the addition of a CO2 sensor. If there is too much air coming into the room where the vent is fitted, (on a windy day for instance) the amount of CO2 in the room will be lowered. When this happens, the sensor recognises the change and the vent closes automatically. Similarly, if people leave the building in which the vent is situated, the sensor will register the associated drop in CO2 levels and close the vent. As CO2 levels rise, the vent is re-opened. Air exits the building via a duct that connects kitchens and bathrooms to the roof line and uses natural buoyancy forces to push air out of the building, much like a chimney.

A low power, carbon efficient system

‘This ventilation system has the advantage of being quiet, with no moving parts. The only power used is a small battery for the opening and closing of the vent. I have built a prototype and installed it at home in my flat, using the VI-Suite to evaluate its efficiency. I’m very pleased to report that the prototype has proved successful and the next step is to build a more refined version for further testing and evaluation in different situations.

‘My current model of CO2 triggered ventilation vent is designed for use with windows in domestic residences; for larger, commercial buildings the physical format would probably need to change a little. For example, within an office building it might be made up of a larger trickle vent that brings in fresh air from outside to under the floor, which is then distributed to the building through grills. A large commercial premises would probably need to have the system built into the structure of the building, to include multiple sensors. One of the huge benefits of my current domestic-scale system is that it is simple to install. It’s easy to fit retrospectively into existing buildings, and using wireless technology for communication with a central hub, can be incorporated into existing smart-home ecosystems.

VI-Suite, air flow and virus transmission

‘VI-Suite can be used for a wide variety of environmental analysis requirements. Another project in which I’m currently engaged, using the VI-Suite software tools, is in partnership with CDCI members Dr Khuong Nguyen and Dr Marcus Winter. We’re looking at how, in a virus pandemic situation such as Covid, travelling on the London Underground might be made safer through creating seating arrangements that make virus transmission between passengers less likely.

‘Part of VI-Suite uses CFD – Computation Fluid Dynamics. CFD uses data structures to analyse issues of fluid flow, including velocity, density and chemical compositions. In this way VI-Suite can predict how air moves through an enclosed space. In the case of the London Underground, air enters the train from outside and then moves through the train within the carriages. One of the stretch goals of the project is to use the VI-Suite to predict where that air will go, and how it will move in relation to the passengers. Through this analysis, we will be able to suggest different ways of seating, to minimise virus transmission as a result of airflow in a pandemic situation.

Improving analysis of carbon expenditure in buildings

‘Another feature of VI-Suite is its function to produce environmental contextual analysis, such as sun paths – a projection of where the sun will be in the sky at a given time – wind roses, shadow analyses etc. By interfacing with a lighting simulation software called Radiance, VI-Suite can predict lighting levels on and within a building. Further contextual building analysis is achieved through interfaces with EnergyPlus, to simulate and analyse energy use in a building, and OpenFOAM for detailed air flow analysis.

‘Building on these earlier applications, I’ve just completed a prototype version of the whole-life carbon element of the program. Although embodied carbon calculation has been around for a while, there are not many embodied carbon calculators – and as far I know, until now there haven’t been any which are embedded within operational energy simulations to allow whole-life carbon simulation and analysis. For this part of the software, I’ve used the University of Bath ICE (Inventory of Carbon and Energy) database. The database holds embodied carbon information on a huge range of different materials, such as brick, cement and plywood, giving details of how much carbon is used for each material. I’ve interfaced the ICE database with VI-Suite to calculate the total embodied carbon in a 3D model, or to embed embodied carbon data into a simplified energy model.

A changing conversation

‘Having worked in the field of energy-efficiency in buildings for twenty-five years, I’ve observed how the conversation has changed in recent times. The building industry is pretty conservative, and while energy efficient technology and techniques have been around for forty to fifty years, the industry has been slow to use the technology that’s available. If anything, I’m surprised by the lack of change in construction. So, while materials such as glass, concrete and steel are still being used by architects and contractors, the conversation is moving towards the advantages of using more sustainable, natural materials and ways of implementing greater energy efficiency. I’m optimistic that this in turn will lead to measurable change in our built environment and it’s exciting to be part of that transformation.’

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