Close the Performance Gap with detailed HVAC simulation

Date Published

7th Nov 2019

Niall Gibson
Business Development Manager, IES

No Planet B

Concern over climate change continues to infiltrate all sections of society.  It is now the only consistent news story, with the daily activities of the Extinction Rebellion campaign coming second only to Brexit. While this isn’t the platform to comment on failed water cannons, and school children skipping classes in protest, there is no doubt that collectively as a society we must address this issue in a focused effort. Silicon Valley’s billionaire techies are engaging in a new age Mars race, but that’s surely a distraction from the most obvious of solutions - resetting Earths natural ecosystem must be a much easier task than transporting the human race to a foreign planet. There is no planet B, only Planet Earth.

We’re lucky here in the UK, as we are world leaders in tackling climate change, with the UK being  the first major economy to pass laws promising to end its contribution to global warming by 2050. This translates to bringing all Green House Gases (GHG) to net zero by 2050. A large proportion of these GHGs are attributed to the Built Environment, around 40%! But did you know that 80% of buildings in 2050 have already been built? Yes, we need new builds to be carbon light, but the focus must be on addressing the impact of the existing building stock.

25 years of IES technology

This year, IES celebrates its 25th birthday. That’s 25 years of a focused mission to optimise the performance of buildings to minimise the carbon footprint and energy demand. IES achieve this by developing its market leading analysis software; the IESVE, the Intelligent Communities Lifecycle (ICL) and associated tools. These tools allow users to analyse the buildings performance at each of their life cycle stages, from Design to Operation. As Lord Kelvin stated “you must first measure it, to improve it”. By enabling understanding of the buildings performance at each of the RIBA work stages and the flow of data between these stages, this results in a better performing building all round. That said, there is one key stage which has proven to be challenging for the industry as a whole.

Closing the Performance Gap

The performance data link between the Design and Operation stages (RIBA work stages 5-7) has been the biggest challenge, but this is where IESVE fits in. Using IESVE and the complementing iSCAN product, you can seamlessly bridge this gap. But the challenge is no longer a technology one - it’s a practitioner one. Here in the UK, simulation has become reliant on the NCM, driven by the approach the UK have taken towards compliance with the EPBD. This has resulted in an interesting regional difference where the UK is almost unique in a lost generation of DSM users who are not experienced in undertaking detailed HVAC simulation. If you were to visit almost any other part of the world, DSM would be synonymous with detailed HVAC simulation but here in the UK this is the biggest challenge to bridging Design with Operation. Ask yourself, if the Design model isn’t representative of the detail of the building in Operation, how can the two ever correlate? 


The Performance Gap is well known, and can be overcome with three components; Technology, Data and Methodology. We have the technology (IESVE) and more than enough data from buildings, which leaves methodology and how we use the technology available. There are a number of methodologies and standards including CIBSE TM54 and ASHRAE IPMVP which outline the approach to overcoming the performance gap and model calibration – the key common denominator being detailed HVAC simulation. Or, in IESVE speak, moving on from using ApacheSystems to using ApacheHVAC here in the UK. 

Abracadabra – easy HVAC with the new HVAC systems wizard!

Not sure about ApacheHVAC? Good news – help is on hand! The HVAC systems wizard was released in IESVE 2019 and helps guide the user through some of ApacheHVAC’s more accessible features. This is a great high level introduction to ApacheHVAC enabling you to take advantage of features such as: CIBSE & ASHRAE Load reports (LARI), Auto-Sizing of plants and a library of NCM HVAC systems to get started quickly. You really don’t need to be an ApacheHVAC expert, the wizard allows you to streamline HVAC systems is just 5 easy steps and is a great starting point and introduction to ApacheHVAC. If you are looking for support for a more comprehensive understanding of ApacheHVAC we also run training courses throughout the year where you are welcome to join us.

So yes, feel free to glue your hands to the road with questionable celebrities, we need to do what we can to maintain awareness of climate change, but you can also fight the fight right where you are with IESVE. As a good first step, why not join me on my next webinar on Wednesday 20th November at 12pm GMT for a demonstration of the new HVAC wizard to see how easy it is to benefit from what ApacheHVAC has to offer.

Latest from DiscoverIES