Mahogany House, 51 Lithos Road, London, NW3 6EY

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Site visit made on 2 December 2025 by M Clowes BA (Hons) MCD PG CERT (Arch Con) MRTPI an Inspector appointed by the Secretary of State Decision date: 23 December 2025 Appeal Ref: APP/X5210/W/25/3371509 Mahogany House, 51 Lithos Road, London NW3 6EY • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Mr Ganiyu Laniyan [Shian Housing Association Ltd] against the decision of the Council of the London Borough of Camden. • The application Ref is 2025/1765/P. • The development proposed is the replacement of existing doors & windows with double glazed flush profile uPVC windows. Decision 1. The appeal is dismissed. Preliminary Matters 2. This appeal is one of 6 proposals for the replacement of timber framed windows within different properties that form part of the Lithos Road Estate1. Each application was submitted separately, so I have determined the corresponding appeals separately and independently of one another, although there are common themes within my reasoning. Main Issues 3.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision The main issues in relation to this appeal are i) the effect of the proposal on the character and appearance of the host building and wider area and ii) whether the proposal is an environmentally sustainable form of development. Reasons Character and Appearance 4. The appeal site comprises a block of flats forming a terrace with 2 other symmetrical houses. The terrace has a strong architectural rhythm and harmony arising from the repeated use of projecting balconies to the front. It visually relates to other buildings within the purpose-built 20th century housing estate which has its own distinct character, in contrast to the traditional terraces located further along Lithos Road to the north-east. Notwithstanding that there are other buildings nearby which have uPVC windows, within the housing estate timber windows and patio doors are the prevalent and original material. As a component part of a wider terrace, the appeal site contributes positively to the appearance of the housing estate and wider area. 1 Appeal references APP/X5210/W/25/3371504, APP/X5210/W/25/3371505, APP/X5210/W/25/3371506, APP/X5210/W/25/3371507 and APP/X5210/W/25/3371508. https://www.gov.uk/planning-inspectorate

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Appeal Decision APP/X5210/W/25/3371509 5. The Camden Planning Guidance; Design (CPGD) 2021 emphasises the importance of materials to the architectural design of a building, noting that the use of poor-quality or an unsympathetic palette of materials can diminish the quality of a well-designed building. The Home Improvements Camden Planning Guidance (HICPG) 2021 expands on this, by strongly discouraging the use of uPVC windows for aesthetic and environmental reasons. Such guidance applies regardless of whether a particular site is a designated heritage asset or located within one. I will return to the environmental considerations in the second main issue below. 6. The installation of double glazing is not in itself disputed by the Council and the CPGD and HICPG do not prohibit the use of uPVC altogether. However, the more contemporary architectural language of the appeal site and the wider housing estate, whilst providing flexibility in material choice does not automatically render uPVC acceptable, given the implications for the proportions of the resultant windows. It is therefore important to assess the specific context of the appeal site. 7.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Although the proposed window and door frames would have a woodgrain finish and similar opening arrangements, they would have chunkier frames and a more uniform finish that would be distinguishable from the existing timber frames. Visibility of the proposed sliding doors would be interrupted by the projecting balconies which draw the eye due to their striking design. The central hallway windows would not be screened in this way but they are relatively small and again subservient in views to the dominant balcony design. 8. Despite the noticeable change to the proposed windows, Mahogany House is not prominent in public views given that the appeal site fronts onto the communal garden. It does not have a substantially different position to Sequoia House located next door, given that both houses form the mid-section of the terrace and front onto the communal garden, albeit I acknowledge that there is slightly more tree planting near to Sequoia House. Replacement uPVC windows were permitted on appeal at Sequoia House recently2 and thus, the proposal would serve to restore to a small degree the symmetry of windows to the wider terrace. 9.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Although the change in framing material would contrast with the prevalent use of timber throughout the estate, its use in a discreet location would not harm the character and appearance of the area overall. The proposed rear windows would be screened from open public view by a high retaining wall and adjacent development. 10. The Council has referred me to 2 appeals at Kilburn High Road for the dismissal of uPVC windows3. However, that site related to an attractive historic building in a prominent corner position such that I do not find it to have a comparable context. 11. For the above reasons, the proposal would not cause harm to the character and appearance of the host building and the wider area. It would therefore accord with Policy D1 of the Camden Local Plan (CLP) 2017 and Policy 2 of the Fortune Green and West Hampstead Neighbourhood Plan (NP) 2015. Together these policies, amongst other things, require developments to comprise details and materials that are of a high quality and complement the local character. 2 Appeal reference APP/X5210/W/24/3349805. 3 Appeal decisions APP/X5210/C/22/3305743 and APP/X5210/W/22/3302064. https://www.gov.uk/planning-inspectorate 2

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Appeal Decision APP/X5210/W/25/3371509 Sustainability 12. Policy CC1 of the CLP requires all development to minimise the effects of climate change and encourages all developments to meet the highest feasible environmental standards that are financially viable during construction and occupation. It supports and encourages sensitive energy efficiency improvements to existing buildings through criterion (d). I have not been led to a specific definition of what would constitute a ‘sensitive’ energy improvement. However, in the first main issue above I have not found harm with regard to the effect of the proposal on the character and appearance of the area. 13. Nonetheless, criterion (f) of Policy CC1 expects all developments including refurbishments, to optimise resource efficiency by using materials with low embodied carbon content, even if it is deemed to be a sensitive energy efficiency improvement4. The explanatory text to the policy explains that embodied carbon is the carbon impact associated with the production, transport, assembly, use and disposal of materials. It does not include the carbon emissions associated with the energy used for heating, lighting or cooling in the completed building. 14.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Therefore, the increase in the Standard Assessment Procedure rating for the energy efficiency of the dwellings by 5 points, and the high thermal performance of the proposed windows whilst important (U-value of 1.1 W/m²K), is not the only or primary concern of the policy. The suggested reduction in energy consumption relies on assumptions of energy sources for the building and does not take into account actual usage of the residents within the appeal site, such that I do not find it a credible calculation. 15. In any event, it has not been demonstrated that the proposed uPVC windows and doors would have a better thermal performance than other material choices such as timber, or that they could not address the water ingress, decay and draught penetration the appellant reports. No specific evidence has been submitted to substantiate the appellant’s claim that uPVC is durable, recyclable and has a lower embodied carbon footprint compared to FSC-certified hardwood. 16. In contrast, the HICPG strongly discourages uPVC windows for environmental reasons.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision It states that timber window frames have a lower embodied carbon content than uPVC and aluminium versions, including emissions from extraction, refinement, transportation and processing. The CPGD also references the inability of uPVC to biodegrade. 17. To support this position, the Council has also provided numerous academic and other independent studies that recognise timber as a sustainable material that with maintenance, can last longer than uPVC5. The Roma Tre University review found that wooden frames generally have low levels of embodied energy and carbon dioxide emissions relative to their production processes. uPVC windows in contrast were found to be more energy intensive and responsible for high emissions of harmful by-products such as hydrocarbons, dioxins, vinyl chloride, phthalates and heavy metals. Wood is consistently attributed by the academic and other sources as having the lowest embodied energy and the best environmental 4 As set out in paragraphs 8.17 and 8.18 of the explanatory text to Policy CC1 of the CLP.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision 5 Including but not limited to, ‘Embodied Energy and Embodied GWP if Windows: A Critical Review’ by Asdrubali et al of the Department of Engineering, Roma Tre University 2021; ‘Double or Triple Glazing? All Pane and No Gain?’ by Circular Ecology 2014 and ‘Whole Life Analysis of Timber, Modified Timber and Aluminium Clad Timber Windows’ by the Institute of Building and Urban Design at Heriot-Watt University 2013 as provided at appendices F-H of the Council’s Statement of Case. https://www.gov.uk/planning-inspectorate 3

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision 5 Including but not limited to, ‘Embodied Energy and Embodied GWP if Windows: A Critical Review’ by Asdrubali et al of the Department of Engineering, Roma Tre University 2021; ‘Double or Triple Glazing? All Pane and No Gain?’ by Circular Ecology 2014 and ‘Whole Life Analysis of Timber, Modified Timber and Aluminium Clad Timber Windows’ by the Institute of Building and Urban Design at Heriot-Watt University 2013 as provided at appendices F-H of the Council’s Statement of Case. https://www.gov.uk/planning-inspectorate 3

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision Appeal Decision APP/X5210/W/25/3371509 performance. They therefore reinforce what the guidance within the HICPG and CPGD seeks to achieve in conjunction with Policy CC1 of the CLP. 18. The appellant has not sought to dispute the findings of these studies nor provided a specific comprehensive assessment on resource efficiency/embodied carbon energy of the proposed windows compared to possible timber or other alternatives. For this reason, I find that it has not been demonstrated that the proposed development would optimise resource efficiency by using a material with a low embodied carbon content, as required by Policy CC1. 19. I have reached a different conclusion on the scheme’s compliance with Policy CC1 of the CLP to the Inspector in the Sequoia House appeal6. This policy requires all 6 of the first criteria to be satisfied to demonstrate appropriate climate change mitigation, not just whether it amounts to sensitive energy efficiency improvements7. The appellant has failed to demonstrate that the expectations for new development as described in the supporting text to Policy CC1 have been met. My findings on this issue are consistent with the Inspector for the Kilburn High Road appeals. 20.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision I find that the proposal would not be a sustainable form of development. It would conflict with Policy CC1 of the CLP, as set out above. Other Matters 21. The Council permitted aluminium replacement windows in Laurel and Sandalwood House’s. I have not been provided with any information other than the decision notice and plans which explains the reasons that the Council came to these decisions. Be that as it may, aluminium is a different material to uPVC such that the proposals are not like for like. The decisions were also made prior to the adoption of the HICPG and CPGD. This does not affect my findings. 22. A petition has been submitted in support of this proposal including signatories from different houses within the housing estate. Support for a proposal does not indicate a lack of harm but I recognise the benefits that the proposal would have to the residents from improved thermal insulation, security and noise reduction. However, I am not satisfied based on the evidence presented, that such benefits could not be achieved by alternative materials. Neither has it been demonstrated that ongoing maintenance or other alterations such as secondary glazing could not provide similar benefits to the residents.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — Appeal Decision This attracts limited weight. Conclusion 23. I have found that the proposed development would in this particular context, not be harmful to the character and appearance of the host building and the wider area. The absence of harm is however, neutral in the planning balance. The limited benefits of the scheme in this instance do not outweigh the harm identified in respect of sustainability and the associated conflict with the development plan. There are no considerations of sufficient weight to indicate that a decision should be made otherwise than in accordance with it. Accordingly, the appeal should be dismissed.

Mahogany House, 51 Lithos Road, London, NW3 6EY — London Borough of Camden — M Clowes - INSPECTOR 6 Appeal reference APP/X5210/W/24/3349805. 7 As indicated in the wording of Policy CC1 with ‘and’ linking criterion a-e with f. https://www.gov.uk/planning-inspectorate 4