f MOBs Phase 3: Task 4 - Ventilation Report

There is a requirement for gas distribution network (GDN) operators to understand the cost, safety, and practicality of converting network pipelines from Natural Gas to Hydrogen in multi-occupancy buildings (MOBs). Previous work undertaken during project ‘MOBs Work Pack 2 Asset Information Review’ [1] considered the requirements for pressure testing, commissioning, and decommissioning of MOBs following a conversion to Hydrogen, and identified the following gaps in technical evidence.
“How does Hydrogen affect the requirements for ventilation and explosion relief?”
“Work is required to understand the ventilation requirements of meters installed inside dwellings, whether existing ventilation in MOBs is adequate and the practicalities of increasing the ventilation should it be required. Work has already been undertaken under the NIA project ‘NIA_WWU_2_12 – Ventilation Within Buildings’[2]. It was proposed that ROSEN review the NIA_WWU_2_12 work and confirm its applicability to MOBs”.
"Further work is required including a study consisting of a review of relevant British Standards (BS 8313 [77], BS 6891 [75] and BS 5925 [78]) and validation through case studies to determine how duct dimensions and ventilation requirements are affected by Hydrogen. This work would also need to determine whether the size and positioning of existing vents are adequate with Hydrogen.
“Further work is required to determine whether the ventilation in dwellings is adequate for risers and laterals located within and passing through dwellings.”
SGN is leading a feasibility project with some applied testing to understand the steps needed to convert MOBs to Hydrogen, including any testing required to address any evidence gaps. This report focuses on the ventilation requirements associated with the conversion of MOBs from Natural Gas to Hydrogen. The objectives of this task are to:
• Determine ventilation requirements for meters, risers and laterals inside buildings.
• Determine ventilation requirements for typical meter banks and energy centres with Hydrogen and how they compare with ventilation requirements for Natural Gas and update Table 6 of IGEM/G/5 Edition 3 [2]
• Determine ventilation requirements for typical ducts with Hydrogen and how they compare with ventilation requirements for Natural Gas and update Table 8 of IGEM/G/5 Edition 3.
• Investigate the feasibility of adding ventilation to MOBs which will need to be positioned so as not to compromise fire safety if located in a fire compartment.
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.