CIBSE TM69 Publication Webinar- Dynamic thermal modelling of basic blinds- 21st February 2023

In October 2022, CIBSE published a new Technical Memorandum on the Dynamic thermal modelling of basic blinds (TM69). The initiative of this publication came from the CIBSE Building Simulation Group, and several individuals, companies and organisations were involved in reaching this milestone. The main authors of this publication are Prof Darren Woolf from Wirth Research, Dr Bahareh Salehi from Mott MacDonald, Maria Gabriela da Silva Costa from Useful Simple Trust, and Elpida Vangeloglou from Etheras Ltd. An interview with the authors was conducted by CIBSE to find out more about this publication and get a glimpse into what it was like being a CIBSE TM author, which can be found here: An interview with the authors of TM69.

Initially, this guideline was briefly presented at the Build2Perform 2022 event as part of the CIBSE Building Simulation Awards (CIBSE BSG Awards 2022).

TM69 was then unveiled in more detail at #GrowYourKnowledge webinar on the 21st of February 2023 which hosted more than 500 attendees from all around the world, including the UK, Ireland, Hong Kong, Australia, India, UAE, Italy, Belgium, Canada, Brazil, USA, Spain and many other countries. Link to the recording is: Registration (gotowebinar.com).

During the webinar, the main TM69 publication topics included were:

• Heat transfer through glazing and thermal comfort.
• Heat transfer through glass-blind system .
• Glass-blind performance where a case study was modelled to analyse the effect of internal simple blinds (considering parameters such as surface colour and air gaps) on air temperature, mean radiant temperature and operative temperature when assessing overheating risks and heat load calculations.
• Live application to show how to model a simple blind using a dynamic thermal modelling software tool whereby the workflow of blind modelling was discussed. 
• Best usage in terms of applying blind models within regulatory, performance and/or compliance assessments, visual comfort, thermal comfort, natural ventilation, energy, heating and cooling loads, façade design, acoustic and operability of blinds.
• Emerging themes including complex blinds and possible uncertainties when modelling blinds.

There were also several interesting questions and points of discussion raised between the attendees and the authors during the webinar which have been highlighted below:

• In Germany there is a requirement to calculate cooling load with blinds closed. What is your idea and vision of how to properly calculate cooling load calculation?
• This is the best method for calculating cooling load in a building as blinds must be considered as the main part of the building. In this publication, the term “glass-blind system” is used which refers to the fact that window and shading devices should be considered as one piece. So, in the ideal situation, blinds must be closed (preferably with automated control) at some specific time of the day depending on the solar irradiance and internal temperature. 
• Are engineers likely to be comfortable with modelling cooling loads with blinds down? This would not represent a worst-case scenario in terms of peak gains, and they would not want to receive complaints about overheating in the event that blinds are not lowered on a particularly hot day and the system/emitter doesn't have sufficient cooling capacity to achieve the set point.
• Is there a recommended software? 
• Within the publication, various software tools are compared, and it is up to the user to choose the most suitable software tool for a particular project.
• Are there any recommendations of specific thresholds for internal/external temperature and external solar incidence for raising/lowering blinds?
• On the topic of thresholds to lower/raise blinds, it is difficult to recommend one standard approach applicable to all scenarios, given that blinds could be controlled manually (user behaviour would dictate how they are controlled) or automatically (a more defined approach can be followed). In the guide, we provide ranges within Table 3. Good practice would be to carry out model optimisation and discuss with the blind manufacturer, prior to explaining the impact of control thresholds to the design team and incorporating them into the Operation and Maintenance Manual. In a future advanced blind publication, it would be good to incorporate an evidence base on strategic control applications as well, for which supporting data would be needed. 
• Is there a test standard method for the thermal properties of the blind material, e.g. the conductivity, LW emissivity and LW transmittance?  
• For detailed input on test methods for product performance, it is good practice to contact the manufacturer. We would also recommend referring to the below documents, alternatively contact ES-SO or BBSA for more information. 
• BS EN 14500:2021 Blinds and shutters, Thermal and visual comfort. Test and calculation methods (London: British Standards Institution)
• BS EN 14501:2021 Blinds and shutters. Thermal and visual comfort. Performance characteristics and classification (London: British Standards Institution)
• The recent Part O Regulations is fairly strict in that it states blinds should not be used in the modelling to reach compliance, do you think this will change with this update? Could you please provide an explanation that this document (TM69) supports overheating analysis as blinds cannot be used to comply with Part O?
• As long as a sensible approach is applied to façade performance and glazing ratio so that solar gains are managed at the first stage of the cooling hierarchy, then the internal blind can be complementary to that. This guide aims to support the modellers to better represent the use of internal blinds beyond compliance only.  As the industry upskill in modelling dynamic building performance, building regulations might take a different approach in the future, but we are not in a position to comment on that. 
• What’s the current guidance on blinds from a Part L perspective? Previously we haven't modelled blinds for Part L as it is a risk to commit to it.  
• Internal blinds are not frequently used in compliance modelling, but they are accepted as a solution to control solar gains for Criterion 3. The need to close the performance gap does incentivise operational energy assessments as standard practice and it is therefore hoped that the value of blinds in reducing energy use intensities and peak loads will encourage design teams and developers to commit to blinds as part of their base build design.  
• How do you assess the impact of wind blowing through gaps in poorly draught-sealed openable windows? 
• In most dynamic thermal modelling exercises an assumption is made on the air permeability of the building considering its age, location, height and services, typically using the CIBSE Guide A tables. A more refined level of modelling would be to assign crack flow coefficients to the openings, considering the opening characteristics and pressure differentials. However, if a detailed analysis of the air flows through such gaps is required to answer specific questions on the building’s performance, then advanced modelling using computational fluid dynamics (CFD) would be appropriate. 
• What was the reason for not using ISO 52022-3:2017 instead of ISO 52022-1-2017?
• The former Standard would be more aligned with a future advanced blinds publication. That said, it is still applicable for the basic blinds and would result in a more accurate calculation of gtot compared to the more simplified method adopted using the latter Standard.

We would like to express our sincere gratitude to all involved in this publication, we look forward to the next chapter of this publication, which will be focused on advanced blinds. If you have any experience or case studies related to the use of advanced blinds, please get in touch with the team of authors on buildingsimulation.info@cibse.org.

CIBSE BSG Event – NABERS UK through the lens of a modeller and two members of the IDR – 11 October 2023

 

The CIBSE Building Simulation Group hosted a hybrid event aimed at NABERS UK and its impact on our industry where industry experts and professionals gather to explore the past, present, and future of NABERS UK.

Darren Coppins, Built Physics, one of the leading figures in assisting the initial implementation of NABERS UK (and also 1 of 11  Independent design reviewers for NABERS UK), introduced and provided the wider context of NABERS projects in the UK; later provided a scheme update, and detail as to where additional resource and training can be found (notably via the software agnostic CIBSE advanced simulation modelling for DfP course), to build on many of the topics covered in the event. Key points from the scheme update are:

• NABERS UK is governed by the NABERS Scheme which is owned by Australia’s New South Wales Government.
• BRE has Chosen to terminate it’s agreement to administer the UK scheme for NABERS.
• The BRE have committed to continuing to support NABERS UK until a new administrator is appointed.
• With the NABERS UK rules governed by NABERS and the wider steering group, no changes to rules are expected as part of this transition.
• NABERS UK is expected to continue to grow to cover other building types, which are already covered by the Australian scheme.

Owen Boswell, Hoare Lea, discussed his perspective as a modeller, as well as engagingly touching on the significant opportunities and insight modelling presented for the wider team, and common issues he has encountered with projects he has worked within. Key advice being to:

• Initially take a step back and gain a wholistic view of the project, its context and early stage opportunities, e.g., architecture.
• The need to really work with the unique context of the building, not simply take previous traditionally adopted strategies, and leverage the insight modelling provides to help understand operation, and inform the ongoing design decision.
• Cover the less glamorous, but equally important, and often overlooked administrative side to make the modeller’s/project team’s life more straightforward.

Owen also discussed his experiences of independent design reviews and the transparent, honest collaborative approach with the objective to maximise the potential for the buildings involved. A real opportunity to learn significant amounts for all involved and take these lessons forward. Finishing his presentation with a case study, highlighting utilisation of a district heat network and some of the unique associated  risks for these cases.

Hugh Gordon, Hilson Moran, and Claire Das Bhaumik, Inkling then discussed their perspectives as Independent Design Reviewers (IDRs). Hugh presented the purpose of modelling for DfP projects, reaffirming  many of Owen’s points, from an IDR perspective, to reinforce the significant value of modelling which is commonly overlooked and can be drawn upon to inform and assist the design process-rather then simply reflecting the likely outcome. Digging further into how some of these issues could be analysed and resolved at earlier stages. (referencing some of the initial projects reviewed).

Claire presented much more detail as to how simulation can really be improved, and common points which are frequently missed within NABERS projects:

• The importance of controls and how these should be modelled and detailed. 
• How to analyse specific, context dependent, risks to the project; enabling more insight as to likelihood and consequence, as well as how these can be mitigated against.
• The need for the building to really perform, and the insight into sizing/control/efficiency that modelling outputs related to: unmet hours, and thermal comfort outputs can provide.
• How the multiple sources of energy draw which make up the overall consumption of a building, not simply consumption linked to building services should be included and fully defined to ensure it is an accurate reflection of the reality.
• The need to accurately project how much building energy PV will truly displace-particularly over non-occupied hours (such as Sundays) for larger PV arrays.

For more details, see the slides and to watch the whole event and very interesting Q&A head over to Youtube. 

It was  great to see the significant collaboration for this event, which is a good mirror as to what is necessary for the design for performance projects themselves: illustrating the steps which are necessary, and now being taken to help the measurably, and transparently performing buildings the industry, and our clients need, are striving towards, and will be necessary if the wider trajectory to efficiency, and, Net Zero objectives, are to be met.

CIBSE BSG Event – Overheating: Approved Document O – 20 October 2022

 

The CIBSE Building Simulation Group hosted a hybrid event aimed at modellers tackling Part O assessments using the Dynamic Thermal Modelling approach. 

The event was led by three experts: Ben Abel of Hilson Moran, Jack Harvie-Clark of Apex Acoustics, and Susie Diamond of Inkling, who shared their thoughts and recommendations on what they believe are the most challenging and confusing aspects of Part O assessments. They emphasised the need for consistent and appropriate approaches to these assessments, and highlighted some of the most confusing and tricky aspects of the analysis.

For more details, see the slides and to watch the whole event and very interesting Q&A head over to Youtube. 

One of the key issues discussed was the confusing terminology surrounding window geometry. The term "free area" is often used in Part O when what is really meant is "equivalent area." However, free area also has another definition, which is the total size of the opening. This can lead to confusion and errors when modelling windows for Part O assessments.

To address this issue, the experts recommended using "free area" and a calculated discharge coefficient when specifying natural ventilation openings and communicating with acousticians. They also reminded modellers to factor in the Part O max 650mm reach from the inside wall limit when assessing window openings.

Modelling opening windows is a complex task, as different terminology is used to describe flow performance through openings. The effective area is the product of the free area and the discharge coefficient (Cd), while the equivalent area is the area of a circular hole in a flat plate that achieves an equivalent flow performance as the opening being assessed. The flow performance of a partially open window will always have more friction, which means that the calculated discharge coefficient for any window opening is always less than 0.62.

Another important issue discussed was the impact of site night time noise limits on bedrooms. If these limits are exceeded, it is essential to understand from an acoustician where and by how much and to model accordingly. There is a hierarchy of possible solutions for night time noise depending on the severity of exceedance and the site location. Ideally, these solutions should be sized on night time bedroom demand rather than daytime for the whole unit.

To ensure consistency with acoustic calculations, the experts recommend entering the window as fully openable and reducing the discharge coefficient to the value calculated for the window. This method should create the same effective area within the models, which is what they base their air flow calculations on.

Finally, the experts advised modellers to use the Future Homes Hub (FHH) free spreadsheet developed for the simplified method to factor in the Part O 650mm reach limit. This spreadsheet asks for all the window dimensions and the "Distance [a] from inside wall to window frame (mm)," and then calculates the maximum opening angle within the 650mm reach limit and the consequent free area and discharge coefficients using the same algorithm as is embedded in the discharge coefficient calculator spreadsheet.

In conclusion, Part O assessments using the Dynamic Thermal Modelling approach can be challenging due to the confusing terminology and complex calculations involved. However, by following the experts' recommendations and using appropriate tools and spreadsheets, modellers can ensure that their assessments are accurate, consistent, and appropriate.

If you are interested to know more, read this interesting article written by one of speakers, Susie Diamond of INKLING. 

CIBSE Building Simulation Group Awards 2022

The CIBSE Building Simulation Group Awards 2022 was a remarkable event that recognised the exceptional contributions made by young engineers and sustainability consultants in the field of building simulation. The ceremony was hosted by the CIBSE Building Simulation Group, which takes pride in organising two awards every year: the Building Simulation Award and the Building Simulation Young Modeller Award.

The agenda of the event comprised presentations by the finalists of the Building Simulation Award, the introduction of the finalists of the Young Modeller Award, an overview of the activities of the Building Simulation Group, a presentation on TM69: Dynamic Thermal Modelling of Basic Blinds, and the presentation of awards by the judging panel.

The shortlists for the Young Modeller Award included some of the most talented young professionals in the field of building simulation, including: 

• Shweta Salvankar of Cardiff University;
• Anmol Mathur of CoLEAD LLP;
• Priyankadevi Murugappan of WSP-Middle East/Heriot-Watt University;
• Reema V Xavier of Useful Projects; 
• Vinit Gala of Cyclone Energy Group; and 
• Vinuki Arachchi of Alpin Limited/Heriot-Watt University. 

The winner of the CIBSE Young Modeller Award 2022 was Shweta Salvankar of Cardiff University, with special commendation for the award runner-ups Anmol Mathur and Priyankadevi Murugappan, who were highly commended as very worthy candidates, understanding and advocating the importance of building simulation.

The Building Simulation Award, on the other hand, focused on the use of building simulation in projects and aimed to encourage innovation in building simulation techniques. Out of the numerous entries received, six finalists were shortlisted, including: 

• Jonathan Reynolds of Arup;
• Veichali Mahendra of Hilson Moran; 
• James Crowley of Hilson Moran; 
• Farah Husayni of XCO2; 
• Daniel Sánchez-García of the University Carlos III of Madrid; and 
• Haitham Al Rasbi of the University of Nottingham. 

The winner of the CIBSE Building Simulation Award 2022 was Daniel Sánchez García with exceptional work on a python package to transform PMV based into adaptive setpoint Energy Plus models. Runner-ups for the award were Jonathan Reynolds of Arup and Veichali Mahendra of Hilson Moran.

The event received submissions from all around the world, including the UK, Spain, Uganda, UAE, India, and the USA, among other countries. The pool of submissions included graduates, sustainability consultants, post-graduate, and PhD students, covering various modelling categories such as energy, thermal environment, ventilation, lighting, plant and renewable energy systems, urban and micro-climate, and airborne infection.

The event also included an overview of the activities of the Building Simulation Group by the chair, Prof Darren Woolf, and a presentation on TM69 publication by Dr Bahareh Salehi of Mott MacDonald.

In conclusion, the CIBSE Building Simulation Group Awards 2022 was a grand event that celebrated the achievements of young professionals and experts in the field of building simulation. The event showcased some of the most innovative and ground-breaking projects from around the world, highlighting the importance of building simulation in creating sustainable and energy-efficient buildings. Congratulations to all the winners and runners-up of the awards, and we look forward to seeing more exceptional work in the years to come.

Before closing, we would like to express our sincere gratitude to our sponsors: DesignBuilder, EDSL Tas, ESI, IES and Monodraught. Your support for the CIBSE Building Simulation Awards is greatly appreciated and we are proud to have your continued involvement in this important event. Your contributions have helped us to recognise and celebrate the outstanding achievements of individuals and teams in the building simulation industry. Thank you once again for your generous support.

CIBSE BSG Event – Updates to Part L2A – 29 September 2022

 

The CIBSE Building Simulation Group hosted a hybrid event focusing on the updates of the Part L, Volume 2: ‘Buildings other than dwelling’.

In the shift towards a Future Buildings Standard, the government has introduced a range of changes to the Building Regulations, including Part L, Volume 2: ‘Buildings other than dwelling’. This is into effect on 15th June 2022 and has introduced an uplift in standards. 

We were pleased to host Baran Tanriverdi from Mott MacDonald and Monika Potomska from Sweco, who presented the major updates to the regulations in comparison to Part L 2013, showcased a few case studies comparing the performance between Part L 2013 and 2021, and discussed what might be still missing and the potential changes that might come in the future.

The main takeaways from the presentation are: 

• The emphasis of Part L 2021 is on Fabric First Approach. We are going to be seeing new buildings which are looking much different from what we're used to, with more solidity and better façade performance being key to efficiency.
• Uplift in all building services efficiency and performance standards on reference and notional numbers will necessitate the design to focus on better-performing system solutions in the actual building. The design teams may need to test different system iterations and efficiency measures to achieve above and beyond performance. This is an interim step for FBS and aspirational for better-performing buildings.
• A real push on green technologies with Part L methodology favouring PVs and heat pumps. 
• It's going to be much harder to reach local and regional targets (especially the Greater London Authority (GLA) requirements). Although targets have remained the same it is now much harder to achieve those. Early stage design optimisation will be crucial. 
• Primary Energy (PE) became a principal performance metric along with the Emissions rates. The proposed CO2 emission factor is lower for electricity than for fossil fuels, including Natural Gas, while the proposed PE factor is higher for electricity than for Natural Gas. This may result in a high PE energy impact in some cases where electricity has been chosen as heating fuel. In some cases, a lower reduction in PE is achieved for Electricity rather than for Natural Gas. As a result, the actual building may need to include additional measures to enhance energy performance
• There's a real shift towards reporting Energy Use Intensity (EUI) rather than just using carbon emission as a metric for achieving compliance. There are currently no requirements just targets to consider but calculation methodologies such as TM54 or Design for Performance (DfP)/NABERS are gaining traction with desire to predict actual energy use. 
• The changes to Building Regulations are all based on industry standards such as RIBA 2030 Climate Challenge/LETI/UKGBC. These are interim before Future Building Standard is introduced in 2025. Understanding the key changes to current regulations gives us an insight as to what is yet to come.

For more details, see the slides and to watch the very interesting Q&A head over to Youtube. 

CIBSE Building Simulation Awards at Build2Perform 2021

The CIBSE Building Simulation Group held its Annual Prizes as part of the Build to Perform 2021 programme; the CIBSE Building Simulation Award; and the CIBSE Building Simulation Young Modeller Award.

Darren Woolf, chairman of the CIBSE BSG group, introduced the CIBSE Building Simulation Award which focuses on the use of building simulation in projects, and aims to encourage innovation in building simulation techniques. Our 6 finalists from Wirth Research, United Arab Emirates University, Cardiff University and London South Bank University, presented their exemplar projects followed by the judging panel’s brief questions. 

• Wirth Research - Covid-19 and the work environment, a multi-tool modelling approach to estimate infection risk within office spaces
• United Arab Emirates University - Design of library extension featuring a parametric dynamic facade in UAUE campus
• Cardiff University - Optimisation of modular photobioreactor retrofit
• London South Bank University - Critical evaluation of four building simulation software packages when modelling shading devices in relation to thermal retention
• Wirth Research - Multiscale computational model of existing industrial bakery, performance-based design of ventilation system with CFD

Patricia Pino, from Wirth Research, was announced the winner, for her presentation on Covid-19 infection risk modelling. Patricia presented her methodology that designers can use to understand the risk within their spaces, and where appropriate develop strategies to mitigate it. This can involve changes to HVAC systems or internal layouts and/or generating protocols for the occupancy or general use of the space. 

The two runners-up were Ketki Mehta, of Cardiff University, for her modelling of modular photobioreactors, which was commended for being such an original model; and Deema Al Qahtani, of United Arab Emirates University, for showcasing how a number of modelling tools can be joined together to provide a holistic solution.

Nishesh Jain, of University College London and Design Builder, was the recipient of the Young Modeller Award. The CIBSE Building Simulation Group was very impressed with the continuous support to the industry, academia, publications and participation in publications such as the CIBSE TM63 and TM54. All of these along with his partnership with ASHRAE and IBPSA showcase how he is advocating building simullation locally and also abroad.

Special commendations for their outstanding work have been awarded to Bahareh Salehi of Loughborough University and Thomas Avery-Hickmott of Wirth Research.

Once the finalists had completed their presentations and while the judges headed off to deliberate. Darren Woolf has chaired a panel with our sponsors - David Cocking of Design Builder, Richard Tibenham of IES, Nick Hopper of Monodraught, Fred Mendonca of OpenFOAM, Richard Szoeke-Schuller of SimScale and Alan Jones of EDSL - on the CIBSE Building Simulation Group Vision 2050.

The video of the event can be seen below.

CIBSE Building Simulation Awards at Build2Perform 2020

 The CIBSE Building Simulation Group held its Annual Prizes at Build to Perform 2020; the CIBSE Building Simulation Awards; and the new CIBSE Building Simulation Young Modeller Awards.

Darren Woolf, chairman of the CIBSE BSG group, introduced the CIBSE Building Simulation Award which focuses on the use of building simulation in projects, and aims to encourage innovation in building simulation techniques. Our 6 finalists from Artelia, Atelier Ten, chapmanbdsp, Cundall, Hilson Moran and WSP, presented their exemplar projects followed by the judging panel’s brief questions. 

• Artelia - Innovative Method to minimize simulation & analysis time
• Atelier Ten - Jewel Changi Airport
• Chapmanbdsp - Manoel Island
• WSP - Modelling the World’s Tallest Tower
• Cundall - Optimisation of overheating assessments for residential and commercial buildings using python in IESVE
• Hilson Moran - Healthy Cities

Meredith Davey, from Atelier Ten, was announced the winner, for his presentation on Jewel Changi Airport. The project, which included the world’s largest indoor waterfall, stood out to the judges for the attention to detail and the methods used to understand the implications of the design desires, particularly in relation to the effect that aspects of the design would have on thermal comfort.

The two runners-up were Shane Orme, of WSP, for his modelling of the world’s tallest tower, which was commended for the representation of physics; and Adrien Dumolard, of E-nergy, for his innovative method to minimise simulation and analysis time.

The event this year included the new Young Modeller Award. With the CIBSE Building Simulation Young Modeller Awards we recognise the outstanding contributions of young engineers, apprentices and sustainability consultants working with building simulation and encompassing any type of simulation for the built environment.

Weijun ‘Allen’ Mei, of Cyclone Energy Group, Chicago, was the recipient of the first Young Modeller Award. His submission included 140 models on which he had worked , and Mei was praised by the judges for his advocacy of performance-based compliance and modelling support design, and improving commercial software development. His work helping students to be more exposed to real-world modelling practices through universities and mentoring was also noted.

A high commendation was awarded to Nishesh Jain, PhD student researcher at the Institute of Environmental Design and Engineering at University College London, in recognition of his outstanding work on knowledge transfer and making building simulation design accessible.

Once the finalists had completed their presentations and while the judges headed off to deliberate. Our sponsors - David Cocking of Design Builder, Andrew Hilmy of EDSL, Eric Roberts of IES, Naghman Khan of SimScale and Nick Hopper of Monodraught - presented some of their latest developments and took part in a discussion on the future of the building simulation. They were asked the following question and their responses initiated a great debate. 

“ What are the major trends you are seeing in building simulation and what you are doing in the next 5 – 10 years to respond to these demands? "

The video of their presentations can be seen below.

https://www.youtube.com/watch?v=lueGRYhblr0