Mesh Energy on the RIBA 2030 Climate Challenge

Date Published

12th Feb 2021

As users of the IESVE and strong advocates of the RIBA 2030 Climate Challenge, we invited Mesh Energy to write a guest blog post for us explaining the Challenge and how they use the IESVE to help aspiring projects meet the rigorous targets set out by RIBA…

What is the RIBA 2030 Climate Challenge? 

The RIBA 2030 Climate Challenge focuses on four key areas around building design and emissions. The Climate Challenge aims to give architects and design professionals a framework against which building emissions and health standards can be improved over the course of the decade to contribute to the reduction in global temperature rises. Targets for 2020, 2025 and 2030 have been set in four areas for both commercial and domestic buildings.


These four areas are operational energy, embodied carbon, potable water usage and health and wellbeing.

Operational energy
When trying to reduce operational energy for RIBA 2030 or otherwise, we suggest using good old common sense and the Mesh Energy Hierarchy. As you work from the top down you give your project the best chance of becoming low energy for the least hassle and capital invested. That’s because all parts of a building’s design and function are not created equal.

The Mesh Energy Hierarchy



By far and away the largest contributors to the overall operational energy usage of a building is the space heating/cooling, ventilation and hot water loads. In most buildings these combined key regulated loads make up 70-80% of the annual operational energy usage.

Embodied carbon
To best understand how to reduce carbon, you have to first appreciate how carbon accounts for the whole life cycle of a material or set of materials to start to tackle the levels of a building's embodied carbon in a meaningful way.

Work done by London Energy Transformation Initiative (LETI), using the Royal Institute of Chartered Surveyors (RICS) Whole Life Carbon Assessment framework gives a window into where carbon lies for a particular building with consideration of all embodied carbon and carbon emissions over the building's lifetime. The table below highlights the distribution for a residential building.



As you break down the individual materials that contribute to the whole building, you will find that they follow a similar pattern; large amounts of carbon in the manufacture, processing and transport of the material to the building site. With regards to the carbon sequestered by the building materials, sequestered carbon is counted at end of life. So, it is important to declare both embodied and sequestered carbon along with the net embodied carbon.

It is truly staggering to think that by the time the building is first occupied that over 50-55% of the total lifetime carbon impact is already in the building!

Fundamentally, there are four key things to consider to meaningfully reduce embodied carbon in a building:

1.    Repurpose or reuse existing buildings
2.    Reuse, re-manufacture and recycle building materials
3.    Build with low carbon, natural (less processed) materials
4.    Offset emissions (renewable technology or woodland planting)

Potable Water
Potable water - contrary to the standard definition of ‘water that is safe to drink or for food preparation’ - in this context means water used for toilet flushing, bathing, showering, dish washing/food preparation and clothes washing.

For domestic calculations of water usage, the Building Regulations Part G water calculator can be used to determine the usage per person per day. Commercially, the BREEAM water calculator can be used for the most accurate predictions.

In order, the biggest users of water in buildings are:

-    Baths with showers = circa 185 litres capacity
-    Showers = circa 10 litres/minute
-    Washing machines = circa 8 litres/kg dry load
-    Bathroom, kitchen and utility room sink taps = circa 6-8 litres/minute
-    Dual flush toilets = 6-4 litres per flush

No more baths? We have considered the following changes to building and appliance design as progress is made through the 2020s...

•    More efficient bathroom fixtures and fittings
•    Changing traditional bathrooms to wet rooms without baths for future adaptability
•    More efficient kitchen fixtures and fittings over time

What is clear is that with a bit of work with toilet specification it is easy to hit RIBA potable water usage targets up to 2025 by more carefully specifying efficient sinks, toilets and showers that are on the market today. But beyond that point the water used by traditional baths comes to a head. Based on current calculation methodologies, baths in homes of the near future will not be suitable. Design of traditional ‘bathrooms’ will have to be radically altered to eliminate baths without compromising the function of the room. Who knows; there may be room there for some decent low water usage bath product innovation!



Health and wellbeing
Unlike the three previous RIBA 2030 Climate challenge targets, there are numerous elements that form the ‘Health and Wellbeing’ target and these are singular values rather than becoming tighter as the decade progresses. The best practice health metrics look at:

-    Overheating
-    Ventilation and air quality
-    Daylighting
-    Volatile organic compounds (VOCs) and formaldehyde. 

The subtle interplay between the first three metrics daylighting, ventilation and overheating can only be fully explored with accurate building physics modelling. We are well beyond guessing and having full confidence that once built the building will be fully optimised. Furthermore, to reduce the performance gap, system commissioning and post occupancy evaluation (POE) will ensure the building is performing the way it was intended.

The fourth metric, VOCs and formaldehyde reflects the focus on trying to further improve indoor air quality, reduce man-made materials and eliminate chemicals that can contribute to adverse respiratory, allergic or our immune system reactions. Targets for VOCs and formaldehyde can be initially assessed by looking at manufacturer’s product data sheets and measured using sensory equipment once construction is completed.

Why RIBA 2030 is important to the industry
The RIBA 2030 Climate Challenge is important to the industry as it sets ambitions and goals to change the way we have been constructing buildings over the past 200 hundred years, and mitigates against climate change, tackling it head on. The construction industry is one of the biggest producers of carbon on the planet. We need to reconsider the way we do things and challenge the status quo and these targets do just that.

What is most important to Mesh and their clients
Our purpose is to inspire and forge a sustainable legacy, and at Mesh we take pride in being an integral part of the design team enabling clients to achieve their sustainable aspirations. Our clients have strong environmental goals and are very aware of the various solutions available to create sustainable buildings, however what they want to know is how to apply this knowledge to achieve their objectives and, through detailed analysis, find the optimum strategy. 

How IESVE helps Mesh to achieve this?
Our starting point, for a project aspiring to the rigorous targets of RIBA 2030, is to build a model with its construction and profiles in IESVE to benchmark how the design will perform against the targets.

Using this model, we ascertain the heat loss calculations of the building to explore the most suitable renewable technologies to use for heating and hot water. The dynamic part of the simulation allows us to understand the operational energy. The model is then used to assess overheating, natural cooling and ventilation and climate-based daylighting to evaluate how the building performs against the health and wellbeing targets. We share BIM data between IESVE and One Click LCA to calculate the embodied carbon and whole life cycle carbon of the building. 

With this detailed analysis we work with architects to refine the building design to meet the desired outcomes based on the three pillars of sustainability, social, economic and environment. This iterative process allows the design team to strike the fine balance between operational energy, embodied carbon and health and wellbeing to create forward thinking buildings that both we and our clients are extremely proud of.

This blog was written by Mesh Energy www.mesh-energy.com 

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