What is PAS 2035?

Richard Jenkins of Nuaire explains what PAS 2035 is, and how local housing authorities can improve their ventilation strategies

PAS 2035 is the latest publicly available specification for low-energy domestic retrofit from the British Standards Institution (BSI). It provides the specification for the retrofit of domestic buildings and details best practice guidance for domestic retrofit projects.

The framework came into effect from June 2019 following the recommendations of the Each Home Counts review, whose purpose was designed to determine better processes for the retrofit of both energy-efficient and renewable-energy measures. It specifies the following requirements:

  • The assessment of dwellings for retrofit improvements (such as ventilation, heating, and hot water)
  • The identification and evaluation of improvement options (Energy Efficiency Measures or EEMs)
  • The design and specification of EEMs (whether individual measures or packages of multiple measures)
  • The monitoring and evaluation of retrofit projects
  • The installation, commissioning, and handover process
  • The insulation of building fabric elements and airtightness
  • The provision of efficient heating and cooling systems with smart controls, including systems using low or zero carbon (LZC) technologies

Sponsored by the UK Government’s Department for Business, Energy, and Industrial Strategy (BEIS), PAS 2035 works towards achieving the Near Zero Energy Buildings (NZEBs) target in-line with new EU objectives.

How is PAS 2035 different?

PAS 2035 delivers guidance on whole-home quality retrofit work to eliminate problems associated with defects, shallow retrofit, and poor design. By considering the entirety of the property and the environment and tenant lifestyles, no one improvement is made in isolation which can unintentionally damage the overall building performance. This PAS covers such work as:

  • Retrofit programmes promoted or funded by national or local government schemes, e.g. the Energy Company Obligation (ECO)
  • Retrofit programmes initiated   or funded by landlords, including social housing organizations, private landlords in the domestic sector and commercial property portfolio holders
  • Retrofit of individual buildings by their owners   or occupants, including both domestic and commercial owner-occupiers
  • A retrofit that is integrated with and forms part of broader repairs, maintenance, and improvement (RMI) activity related to individual buildings or building stocks.

Furthermore, five new retrofit roles with clear responsibilities and accountabilities have been established to ensure that individuals deliver quality throughout. PAS 2035 specifies the retrofit roles as follows:

  • Retrofit Advisor
  • Retrofit Assessor
  • Retrofit Coordinator
  • Retrofit Designer
  • Retrofit Evaluator
  • Multiple Roles

Each role must have a suitable qualification to be valid. Within this framework, TrustMark holders must comply with this standard when carrying out any domestic retrofit work. All other standards referred to in this PAS are also part of the retrofit standards framework.

PAS 2035 and TrustMark

TrustMark has been established as the new quality mark within the retrofit standards framework and supported by an Industry Code of Conduct, a Consumer Charter, and a framework of technical standards for retrofit.

Those who hold the TrustMark are qualified under an operating framework and can demonstrate to consumers that they have the skills and knowledge to deliver the best practice standards and trading practices in the sector.

PAS 2035 and ventilation

Good ventilation is critically important to the health of the property and its inhabitants.

As air flows through a building, it dilutes the build-up of indoor air pollutants such as condensation dampness, mould, Volatile Organic Compounds (VOC), radon, and carbon monoxide. Mechanical Extract Ventilation (MEV) further removes this polluted air from the property and brings in fresh air.

Furthermore, mechanical ventilation units can recover otherwise lost heat from the extracted air to ensure that the fresh input air is brought in at room temperature. These units are known as Mechanical Ventilation with Heat Recovery, or MVHR.

For an alternative approach to ventilation, there is also the Positive Input Ventilation (PIV) strategy. The unit can be discreetly installed into a loft of a house or into the ceiling void of an apartment building. PIV gets its name by the way it works, which is to pressurise the home through the introduction of fresh, filtered air and pushing out the humid, stale air that has built up in the home.

Today, ventilation units can be equipped with additional filters, such as activated carbon, HEPA, and ePM (Particulate Matter), to provide extra decontamination levels to the property. They are designed with energy efficiency in mind, to run at reduced costs for the occupant while considering the impact on the environment.

To combat the threat of climate change and comply with national statutory standards, a substantial reduction of greenhouse gas emissions needs to be made. To achieve this, significant improvements must be made to the energy efficiency of the UK’s building stock, specifically the vast majority of its 27 million domestic buildings.

Under PAS 2035, existing ventilation will be considered inadequate for the improved dwelling if one or more of the following is apparent:

  • There is evidence of condensation and/or mould growth in the dwelling
  • There is no ventilation system, or the ventilation system is incomplete or not functional
  • There are no undercuts of at least 600mm2 beneath all internal doors and above the floor finish to allow air to move through the dwelling
  • There is no provision for purge ventilation of each habitable room (e.g. by opening windows)

To help mitigate these risks and ensure healthy living environments for years to come, it is essential to ensure that the right ventilation product has been installed into the building by a professional.

Richard Jenkins is residential NPD manager at Nuaire