Designing Low Carbon Buildings
At all stages, from design to installation, we can advise how the external wall insulation element of a project can best meet low- and zero-carbon design requirements. We can show not only how the system can meet or exceed current Building Regulations, but also how Passivhaus, BREEAM and other performance standards can be achieved.
When using Permarock external wall insulation systems, heating demand can be dramatically reduced, conserving energy and reducing CO2 emissions.
Our systems also permit very airtight façades to be created; an important factor in the design of energy-efficient buildings.
Low-carbon buildings may include new-build residential developments, education and healthcare premises, commercial property, public and community buildings, and others. If you are planning a specific scheme in which thermal efficiency will be a priority, please contact us.
Why Specify an External Wall Insulation System?
Permarock external wall insulation systems offer architects and specifiers a range of benefits, such as:
- Designed for Long-Term Compliance: By incorporating an insulated render system (commonly referred to as external wall insulation), new buildings can be designed to not only comply with current regulations but to comfortably exceed them.
- Superior Thermal Efficiency: These systems are designed to deliver the highest standard of insulation, thus enabling exceptionally low U-values and boosting overall energy performance.
- Unbroken Thermal Layer: Integrating external wall insulation into the architectural layout offers designers the flexibility to create a seamless thermal envelope, reducing or eliminating cold bridging throughout the structure.
- Enhanced Airtightness: In new-build constructions, applying external wall insulation can play a critical role in limiting air leakage, helping to attain impressively low air permeability levels across the entire building.
- Occupant Comfort: External insulation can be easily combined with modern heating and cooling systems to stabilise indoor temperatures, enhancing occupant comfort while minimising energy consumption and reducing carbon emissions.
- Noise Reduction Capabilities: When materials such as mineral wool are used as part of the external wall insulation system, they introduce acoustic dampening benefits. This reduces noise infiltration from outside and also contains internal noise, delivering improved sound insulation compared to traditional construction methods.
- Early Envelope Closure: External wall insulation can be installed independently of internal construction sequences. As long as weatherproofing requirements are met, interior fit-outs and other tasks can proceed in parallel, shortening the overall project timeline.
- Limitless Design Potential: A broad variety of finishes—including coloured renders and brick-effect facades—can be applied to suit any architectural vision, giving designers near-unlimited creative freedom in exterior aesthetics.
Design Considerations
Although external walls are an extremely important factor, a number of other important considerations can impact on the design process for low-carbon and sustainable buildings. Examples include:
-
Consider the required U-value or SAP rating, and whether there are space constraints affecting insulation thickness.
-
Choose a system that aligns with the wall construction, building type, design loads, and potential structural movement.
-
Ensure the system meets fire performance standards suitable for the building’s use.
-
High-rises and similar schemes should meet A2-s1,d0 per BS EN 13501-1.
-
Check that the chosen finish (colour, texture, style) suits the building’s design, exposure level, and planning requirements.
-
EWI systems are generally assessed to achieve a lifespan of 30+ years. Permarock options can be specified to achieve over 60 years of lifespan expectancy.
-
Pay attention to how the system integrates at joints, edges, abutments, and with other materials.
-
While aesthetics matter, the finish must also meet any impact resistance demands for the building’s use.
-
System costs depend on insulation type, thickness, chosen finishes, and fixings.
-
Wind loads, traffic levels, and environmental exposure (like pollution) can all influence system and finish selection.
Permarock’s technical team can help clients to develop designs and specification that take full account of these and other factors.
The Passivhaus Standard
The Passivhaus standard’s strength lies in the simplicity of its approach: construct a building that has excellent thermal performance, exceptional airtightness and mechanical ventilation. The standard can be applied to residential, commercial, industrial and public buildings.
Passivhaus buildings typically achieve a 75% reduction in space heating requirements compared to standard practice for a UK new build. The Passivhaus standard therefore provides a robust framework to help the industry achieve the 80% carbon reductions that are set as a legislative target for the UK Government. Passivhaus buildings readily achieve Code for Sustainable Homes Level 4 without the need to incorporate micro-generation.
The core focus of Passivhaus design is to reduce the requirement for space heating and cooling. This can be achieved without compromising comfort or needing to rely on the falling costs of renewable energy technologies.
The Passivhaus Standard requires:
- A maximum space heating and cooling demand of less than 15 kWh/m² year or a maximum heating and cooling load of 10W/m²
- A maximum total primary energy demand of 120 kWh/m²/year
- An air change rate of no more than 0.6 air changes per hour @ 50 Pa.
Achieving the Passivhaus Standard in the UK typically involves:
- Very high levels of insulation
- Extremely high-performance windows with insulated frames
- Airtight building fabric
- Thermal bridge-free construction
- A mechanical ventilation system with highly efficient heat recovery.
Permarock systems have been specified for numerous projects that have achieved full Passivhaus certification, including the 2019 Stirling Prize-winning project, Goldsmith Street, Norwich.
Other examples include:
- Oakmeadow & Bushbury Hill Primary Schools, Wolverhampton (two of the first certified Passivhaus schools in the UK)
- The Centre for Disability Studies in Essex (one of the first non-domestic buildings to achieve Passivhaus certification in the UK)
- Mayville Community Centre, Islington
- Duncombe Barracks, York
- New-build homes in Burnholme, York (see case study)
- New-build homes in Nailsea, Somerset (see case study)
Permarock systems contribute towards high thermal performance, thermal bridge-free construction and airtight building fabric. Our technical services are typically consulted and engaged during the early stages of the building design process to assist in the detailing and the specification of the external wall insulation system.
BREEAM
BREEAM (the BRE Environmental Assessment Method) is the most widely used environmental assessment method for buildings in the UK. The assessment addresses a wide range of environmental and sustainability issues and sets the standard for best practice in sustainable design. This enables developers and designers to demonstrate the environmental credentials of their buildings through a recognised measure of environmental performance. Buildings are then rated with either a Pass, Good, Very Good, Excellent, or, for exemplar buildings, an Outstanding rating. The assessment commences at design stage and is then verified post construction when the final certificate is issued.
Permarock can design external wall insulation systems that meet or exceed BREEAM requirements.
Green Guide to Specification
Specifiers working on sustainable developments require information on the environmental impact and performance of building components and assemblies so that they can assess their buildings against the Code for Sustainable Homes. The BRE’s Green Guide to specification provides a rating system for thousands of typical construction components and assemblies, which designers and specifiers can refer to when making environmental choices in their selection of materials.
The environmental ratings, described in the Green Guide, are based on life cycle assessments (LCAs) which take into account the winning of raw materials, manufacture, transport, assembly, maintenance, repair and replacement, demolition and waste management at the end of life. The Green Guide does not take into account operational performance in terms of potential energy savings of materials or systems with high insulation values or thermal mass.
Permarock’s systems achieve excellent LCA scores, which translate into Green Guide ratings of A/A+.
Help with Low-Carbon Building Design
For design support and advice, please call us today on 01509 262924 or email Permarock@Permarock.com.
