Air Quality Mitigation and Ventilation Strategy — Basement Flat Condition Discharge, Hammersmith

Air Quality Mitigation and Ventilation Strategy Discharging Condition 6 for a Basement Flat at Shepherd's Bush Road, Hammersmith
Location: Jurisdicial House, 2 Shepherd's Bush Road, London, W6 7PJ | Client: Jeremy Li | Services: Air Quality Assessment; Air Quality Mitigation & Ventilation Strategy

A Basement Dwelling Against a Moving Target

Two features make this a more demanding brief than a standard residential ventilation statement. The first is the accommodation itself: a lower ground floor flat has limited façade available for intakes and extracts, and what façade there is sits close to street level on a busy road.

The second is the policy test. The site lies within the borough-wide Hammersmith & Fulham Air Quality Management Area, declared on 3 November 2000 for the annual mean nitrogen dioxide objective and the 24-hour mean PM10 objective. But the council's Air Quality Action Plan 2025-2030, adopted on 16 December 2024, goes further than the national objectives. It requires mitigation at new residential development where the council's 2030 WHO-aligned air quality targets — 10 µg/m³ for NO2, 15 µg/m³ for PM10 and 5 µg/m³ for PM2.5 — are exceeded, and where current and predicted concentrations are within 5% of those limits. That is the requirement Condition 6 recites, and it is a materially tighter test than compliance with the national objectives alone.

We were appointed by Jeremy Li to prepare an air quality screening assessment and a ventilation strategy discharging Condition 6, covering each of the condition's four parts in turn, for the change of use of the lower ground floor of Jurisdicial House, 2 Shepherd's Bush Road, London W6 7PJ, from a language school (Class F1) to a one-bedroom self-contained flat (Class C3), together with a single storey rear extension. Full planning permission was granted by the London Borough of Hammersmith & Fulham on 10 September 2025 under reference 2025/00356/FUL.

Screening the Site

The assessment worked from the nearest monitoring station and from the London Atmospheric Emissions Inventory, interpolated to the opening year, rather than relying on the AQMA designation as a proxy for exposure. We read those figures alongside the Defra background maps and the borough's latest Annual Status Report.

The development's own impacts were screened against the EPUK/IAQM (2017) indicative criteria. The scheme introduces one dwelling, provides no car parking and is required by condition to be car-free. It falls below every indicative screening criterion, and no dispersion modelling was undertaken.

Distinguishing the two tests clearly — the national objectives on one hand, the council's aspirational 2030 WHO-aligned targets on the other — was central to the report. National planning policy does not yet require development to be assessed against the WHO targets, but the condition does, and the strategy had to answer the condition as written.

The Ventilation Strategy

The strategy specifies mechanical ventilation with heat recovery serving the flat, with intake and extract terminations set out on marked-up architect's drawings so that every termination position is fixed and checkable rather than left to the installer.

Termination siting was revised during the commission following site information. The report records that there are no existing penetrations on the host building, and that two restaurant extracts on adjoining premises were identified and designed around — a detail a desk-based specification would have missed, and one that would have caused a genuine problem for the occupants had it been overlooked on a lower ground floor with so little façade to work with.

Ventilation rates follow Approved Document F for the flat as consented, and the filtration tier is matched to the screened concentrations and to the requirement recited in Condition 6. Intakes are set as far from the highway frontage and from the identified commercial extracts as the geometry of the lower ground floor allows.

Outcome

The report addresses all four limbs of Condition 6 and gives the Local Planning Authority a specification tied to approved drawings rather than to generic performance statements. The commission illustrates a recurring theme in London air quality work: the borough's own action plan, not the national objectives, is increasingly what sets the standard a scheme has to meet.