An interview with the authors of Dynamic thermal modelling of basic blinds (TM69)

To find out more about CIBSE’s newest Technical Memorandum, Dynamic thermal modelling of basic blinds (TM69),we have interviewed its main four authors: Professor Darren Woolf, Maria Gabriela da Silva Costa, Dr Bahareh Salehi and Elpida Vangeloglou.

The ultimate goal of the document is to narrow the gap between predicted and actual performance of buildings, recognising the value of blinds in reducing peak energy loads and improving thermal comfort. - Elpida Vangeloglou

Could you tell us about yourselves?

Professor Darren Woolf: I have a number of roles and responsibilities which could lead me to describe myself as a professional juggler.

My day job is Head of Building Physics at Wirth Research. We’re a wind, building physics and product design company specialising in high-fidelity computational fluid dynamics (CFD). I’ve been a visiting professor within the Building Energy Research Group at Loughborough University for over 10 years now and always enjoy the limited time I get to interact with the students and share some of my industrial experiences.

Over the last two years I’ve been supporting a large SARS-CoV-2 ventilation research programmes called AIRBODS from which we’ll be completing our final reporting over the coming months – a very exciting period! CIBSE is a partner.

I also have a couple of CIBSE roles. I chair the Building Simulation Group (BSG) from within which we launched a Best Practice Initiative several years ago leading, ultimately, to TM69.

This is hopefully the first of many publications within the initiative where we focus on better performance-led modelling in support of the climate emergency. 

Finally, I chair a new knowledge generation group called UK Urban Environmental Quality (UKUEQ) representing Resilient Cities Group (RCG) and in partnership with the UK Wind Engineering Society. This is a very exciting publication and CFD-focused initiative covering wind, thermal comfort and air quality in the urban environment. I suggest keeping a look out on the BSG and RCG sites to see what these initiatives generate!

Maria Gabriela da Silva Costa: I am a Principal Sustainability Consultant at Useful Simple Trust, an employee-owned trust comprising of five sister companies with a strong focus on driving change in the built environment through design, engineering and communications.

My background is in architecture and environmental design and I have over eight years of experience in undertaking dynamic thermal modelling for building performance and environmental comfort. 

I am interested in creating places that promote good quality of life for people. 

My role today focuses on applying my expertise to long-term regeneration projects.

During my out-of-office hours, I lead a repair café initiative locally and enjoy facilitating social encounters between different generations in sharing and learning new skills through fixing broken items. I have learned a thing or two about broken vacuum cleaners!

Dr Bahareh Salehi: I spend most of my time working as a building physics engineer at Mott MacDonald which is a global engineering, management, and development consultancy company. I also manage to occupy a few hours a week as an Industry Lecturer at the School of Built Environment and Architecture based within London South Bank University.

In addition to my occupations, I’m an active member of the CIBSE Building Simulation Group (BSG) with the aim of highlighting best practices in using computer simulation codes for building-related applications. I have also recently joined a new knowledge generation group called UK Urban Environmental Quality (UKUEQ) representing Resilient Cities Group (RCG) and in partnership with the UK Wind Engineering Society working on thermal comfort and air quality using computational fluid dynamics (CFD).

I’m generally quite passionate about innovative topics related to energy efficiency that can make a difference to related industries and especially collaborating with both academic and industry groups to drive change.

Elpida Vangeloglou: I am a CIBSE chartered building physics engineer, working independently through my limited company, Etheras Ltd, and a Research Associate at London South Bank University.

I have previously worked as a building physics consultant at Ramboll and Hoare Lea in London. My interest in people’s experience in buildings and our environmental impact has led me to specialise in assessing the indoor environment for health and comfort in support of energy efficient performance-led design, utilising dynamic thermal modelling (DTM) and assessing the benefits of coupling DTM with CFD. Over the past two years I have engaged in research on infection-resilient environments through my participation in the AIRBODS programme.

I have lived and worked in a few countries, including Denmark and the UK, and I’ve had the privilege of engaging with multi-national teams on a large variety of projects. 

I like learning new things from different angles and I look forward to exploring further the interaction between people, buildings and the environment.

Have you worked on any publications other than TM69?

DW: I have supported the generation of CIBSE guides and manuals over many years. This includes the chapter on thermal response and plant sizing in Guide A: Environmental design,  and the ventilation chapter of Building performance modelling (AM11) which we’ll hopefully be updating next year.

Outside CIBSE, I’ve acted as chair of the team working on a publication on the modelling of ventilation for thermal comfort and indoor air quality and co-authored the thermal and occupant comfort chapter in the Passivhaus designer's manual. My input to each of these publications was underpinned by the associated building physics.

GC: TM69 is my first publication with CIBSE, however, I was involved in the methodology testing group for the development of Design methodology for the assessment of overheating risk in homes (TM59).

BS: I have several papers currently under review, and I have managed to publish a few papers as well. The two most recent ones were presented at the CIBSE Technical Symposium in 2022:

• 'Comparison of Real-world Data with Simulated Results to Enhance Building Thermal Retention when using Shading Devices'
  This paper was derived from the results of my PhD highlighting the effect of a blind on thermal retention and the discrepancy between reality and simulation when modelling blinds.
  
  
• 'A Dataset from Synthetically Occupied Test Houses for Validating Model Predictions of Overheating'
  This paper was a result of a collaboration between Loughborough University, London South Bank University and Hillson Moran Ltd and presents the results of a study which creates a new empirical dataset to validate and calibrate overheating models.

EV: As part of my role within AIRBODS, I am currently working on the AIRBODS output publication on infection-resilient building design, which is expected to be published early in 2023.

Additionally, I have participated in the development of the LETI Modelling Guide through the 2021 Workstreams and I have co-authored a few publications on daylight assessments, shading technologies and 'cool materials' for the building envelope in international, European, Danish and Greek journals and magazines. Some examples of these are:

• 'Evaluation of daylight in buildings in the future' – REHVA Journal, 2015
• 'Outdated daylight criteria impede sustainable construction' – Ingeniøren, 2015
• 'Development and analysis of mineral based coatings for buildings and urban structures' – Solar Energy, 2012

What are some of the key areas TM69 expands on?

DW: Through the process of driving better modelling and simulation it’s important that, as an industry, we move away from compliance-led building design and associated thinking towards a science-led, performance-led design approach in support of the climate emergency. We need to do this if, in my view, we have any chance of meeting and exceeding targets that are being tightened and we’ll only be able to achieve this via the promotion of good and best practices.

TM69 clearly identifies a wide range of estimates that may drive the decision-making on systems design if the modelling of basic blinds is not properly thought through in terms of background understanding of the physics as well as the software application.

GC: 

Modelling internal shading systems is a complex task and this guide aims to bring a level of simplicity to it.

It’s a starting point to understanding the key components of ‘blinds physics’ to help in their effective representation in dynamic thermal models. It gives an overview on how to apply these components to different software packages.

It also provides tips on how to take into account real-life parameters, such as installation rules (for example spacing and perimeter gaps), and reviews potential implications on energy performance. 

Lastly, it guides users to good practice blind operation when undertaking natural ventilation.

BS: 

Due to the energy challenges and the target to achieve low-energy or net zero energy buildings, it is important to utilise various methods to reduce energy consumption both for heating and cooling.

One of these methods is using shading devices. However, in some cases, the simulated thermal modelling results do not accurately represent positive impacts in the way that real-world scenarios do. To overcome this issue, it is important to increase the knowledge and interest of both software users and developers to bring them together to be more interconnected.

TM69 is the first step towards achieving this goal. For example it provides the estimations required by modellers, which can eventually reduce the decision-making errors when modelling blinds.

EV: To start with, the ‘Dynamic thermal modelling of basic blinds’ recognises that even basic blinds can be complex to model and require a certain level of understanding and clarity on numerous parameters.

The document endeavours to give a background on the physical processes that take place in a building when internal basic blinds are in use, to underpin the importance of relevant parameters to consider when modelling them and to clarify used terminology.

The content aims to be useful to a modeller, provide them with resources from which to obtain relevant inputs, propose methods to follow and highlight differences and limitations amongst the most commonly used software packages in relation to the modelling of blinds. Additionally, the interaction of the dynamic thermal modelling of basic blinds with other studies and applications is considered, for example with daylight calculations and CFD.

What should the readers expect to achieve by reading the publication in terms of knowledge and best practice in building services?

DW: 

Top of the list is increased confidence in their estimates for thermal comfort and/or energy in buildings with basic blinds.

For example, if a building is naturally ventilated this may impact the opening configuration design and, if mechanically ventilated, sizing and even type of system that could be applied.

It is also hoped that it provides a better understanding of interfacing issues with other tools and building disciplines supporting better balanced and/or optimised designs.

GC: I think that the guide will be a useful tool for modellers by, not only, applying the input parameters correctly, but also by giving them access to best practice approaches and workarounds. In this way, they can feel empowered to better enquiry of outputs from their models and work towards a common language for modelling shading systems.

Non-technical readers might appreciate the complexity of such tasks and teams could find ways to streamline communication and collaboration when undertaking modelling of internal blinds.

The publication provides a useful workflow that all parties involved could use to make the modelling task interactive and add value to the projects.

BS: This guide provides background knowledge on the physics of a window with an internal blind and how these devices can assist in increasing energy efficiency by managing heat loss and heat gain.

Additionally, TM69 can help software users to be more confident when modelling blinds by making the correct assumptions using different software tools. 

This eventually will lead us to a more optimised building design, especially at the design/concept stage and not when it’s too late and the building is complete.

EV: I think the readers should expect to gain a good background of the physics around blinds, how to model them and what the capabilities of some key software programs are. TM69 is hopefully a good reference for how to obtain input data and what are good practice methods to follow. 

The ultimate goal of the document is to narrow the gap between predicted and actual performance of buildings, recognising the value of blinds in reducing peak energy loads and improving thermal comfort.

Lastly, if anyone reading this is thinking about becoming an author and/or contributor, what piece of advice would you give them?

DW: Having a team of early career, female, first-time (CIBSE guide or manual) co-authors on TM69 was an absolute joy and pleasure to experience. The dynamics of this group, its energy and collaborative spirit, are central to the quality and, hopefully, the success of this publication.

We were all passionate about the publication which was a massive boost to it. The process of co-authoring and/or contributing also supports the development of personal networks. 

I hope this experience inspires them to get involved in many more.

The use of video conferencing meant that travelling was not required and one co-author, even, lived abroad. We may only meet as a team face-to-face for the first time when we officially launch TM69!

Look out for the various activities early next year. It will certainly be a time to celebrate and, I think I can speak for the rest of the team, something that we can be extremely proud of for the rest of our lives.

GC: Go for it! If you have an idea or know of a ‘pain point’ that you could have had some better guidance on, speak up. You can start by responding to consultations and getting engaged with groups you are interested in. Join the many committee groups within CIBSE and use your voice. It is not that scary, really.

To be honest, I thought this publication would be a 10-page document and it turned out to become a TM! I never thought I would be here, but I can say that the journey is worthwhile. 

CIBSE has great guidance on writing for new authors and the editing team has been extremely helpful in ensuring our message was clear, properly referenced and peer reviewed.

BS: 

I certainly recommend being an author of these publications as it is surely one of the most rewarding experiences of my career.

Being involved in this publication was a fantastic opportunity to network and engage with a diverse range of professionals and not to mention the knowledge and experience gained as you go along. I would like to thank Professor Darren Woolf, who brought us together and shared his experience with us.

I hope to be involved in more publications in the future and invite more individuals on this exciting journey with me.

EV: I would advise those who are considering becoming authors/contributors to do it! Being passionate or knowledgeable about a topic is really all you need to get started and even someone at an early stage of their career can contribute valuable insight.

In my view, authoring is a lot about teamwork. 

A team that makes space for everyone’s input to be heard and valued has an expanded creativity potential. A big advantage of our times is that you can participate from anywhere you want to be. 

This raises so many opportunities for a variety of backgrounds and dynamics within teams.

I have really enjoyed co-authoring TM69. We had a great environment in the team, we all shared an interest in blinds and their modelling and had complementary experiences, which also helped us grow. Communicating our thoughts openly and being flexible with each other made our collaboration smooth and very pleasant.

Thank you for your time.

You can also find out more about TM69 from our Dynamic thermal modelling of basic blinds (TM69) #GrowYourKnowledge webinar. View recording

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