2 2 Tap 4 Tank 3 3 4 5 5 6 4 1 Services PV panels Forth floor structure (later additions) Rooflights Access / Walkways Access onto roof from Center Block muf architecture/art LLP
4.3 Roof alterations and access 7 8 1 Roof Plan 2-6 Views of the existing roof 7 Roof cowls on South side 8 Roof cowls on North side Existing roof space The existing roof of the East Block, above the third floor Interactive Gallery space is predominantly used to access the upper floors of the north courtyard infill (shown opposite) and also to house / access building services equipment, the atrium roof and other third floor rooflights. The roof is mostly flat with an insulated build up on top of the existing concrete roof slab, the roof build up is covered with concrete paving externally. A metal gangway gives access across the sawtooth roof rover the East Gallery. The plan opposite shows the layout of the roof and the images give an indication of the existing building services (Fig.1). Proposed alterations The proposed ventilation roof cowls for the Interactive Gallery will sit amongst the multiple other items of building services equipment that are already located at roof level. We consider this location for the roof cowls to be an appropriate response, given the impact and relative scale of the cowls in relation to the existing services. The existing high level windows / roof lights are a mixture of metal (assumed aluminium) frame single and double glazed units. Please see overleaf for images of the existing windows. The windows to the South Gallery already have opening window units. The opening units will have new actuators fitted which will link to the Building Management System (software) so that the windows can be opened and closed automatically according to the temperature and ventilation requirements. The rooflights to the North Gallery are single glazed, fixed windows. These will be replaced with new metal frame double glazed opening windows (also fitted with actuators and linked to the BMS). The rooflights over the East Gallery (sawtooth roof) are mostly metal frame double glazed units. Every other unit is openable. The openable units will have new actuators fitted to link them to the BMS. To enable the natural ventilation strategy, furthermore, four of the 56 rooflights over the East Gallery need to be replaced with new openable metal frame double glazed windows. To the extend possible the replacement rooflights will match the existing metal frame systems visually. However the new windows will be specified to comply with Approved Document Part L: Conservation of Fuel and Power, making them more thermally efficient than their predecessors. The proposed specification for the replacement roof light systems is the Ritchlight Monopitch Rooflight; a highly insulated thermally broken aluminium frame glazing system which can be polyester powder coated to match the existing window frame colours (please see the image on the following page). Access The roof level is predominantly surrounded by a parapet wall which is approximately 1190mm high. Additional provisions have been added to the roof to further increase the safety for access; rubber matting, guard rails etc (see images 2-6 left). The roof space is used by either staff or maintenance personnel, not the general public. The position of the new roof cowls does not compromise the existing access to the roof, further more it allows for the roof cowls themselves to be safely accessed for maintenance. Interactive Gallery 19
Site Boundary Science Museum new roof cowls HI EX ON TI BI East Gallery Rooflights 2 North Gallery Rooflights 3 West Gallery Rooflights 4 Aerial Photograph of the existing roof showing the roofcowl positions on the South side 5 Proposed rooflight replacement system AD O R 5 4 1 1 2 3 muf architecture/art LLP
5 Noise Council s requirements for noise from building services plant and vents: Noise emitted by all building services plant and vents shall not exceed a level 10dBA below the existing lowest LA90(10min) background noise level at any time when the plant is operating, and where the source is tonal it shall not exceed a level 15dBA below. The noise emitted shall be measured or predicted at 1.0m from the facade of the nearest residential premises or at 1.2m above any adjacent residential garden, terrace, balcony or patio. The plant shall be serviced regularly in accordance with the manufacturer s instructions and as necessary to ensure that the requirements of the condition are maintained. If at any time the plant is determined by the local planning authority to be failing to comply with this condition, it shall be switched off upon written instruction from the local planning authority and not used again until it is able to comply. Reason - To prevent any significant disturbance to residents of nearby properties and comply with development plan policies, in particular policy CL5 of theconsolidated Local Plan. Statement by the project acoustic consultant, Fabrizio Filippi I note that the condition requires a noise impact assessment and background noise measurements at the location of the nearest residential premises. Having reviewed the plans and tenancies close to the proposed plant I have not been able to locate a nearby noise sensitive residential receiver. In fact, we only have: The Victoria Albert Museum at a distance of approximately 45 m Imperial College at a distance of approximately 70 m Natural History Museum at a distance of approximately 55 m We have also reviewed the preliminary specification of the proposed plant note that the noise emissions of the plant is relatively quiet i.e. around 62dB at 1m at full duty and around 50dB at 1 in low noise mode at reduced load (attached). Considering that at a distance of 45m noise attenuates by circa 33dB we are looking at noise emissions in the region of 29 db (but even lower considering screening) at the closest of the receptors highlighted above. Considering that background noise levels in Central London rarely are below 40dB(A) and that there are no apparent residential premises in proximity of the roof plant, I don t anticipate there being any issues with the proposed plant and with compliance with the RBKC policy. Interactive Gallery 21
3 1 2 1 View from the roof looking south 2 View from the roof looking north 3 Section through East Block looking north muf architecture/art LLP
6 Views Views from the street The sectional drawing indicates the extent to which the roof alterations will be visible from the street level. There will be minimal / no change to the appearance of the existing building from the street level as the roof cowls are obscured by the parapet wall. Views from surrounding buildings The photos and sectional drawing opposite also show the scale of the buildings surrounding the Science Museum. The buildings directly surrounding the Science Museum are all of a similar height and as such we consider their view of the roof cowls to be minimal. From the upper levels of the surrounding buildings the changes to the roof lights will be seen. N S Interactive Gallery 23
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7 relevant policy / summary 7.1 Relevant Policy 7.2 Summary The main planning considerations applying to the site and the associated policies are: CL1 Context and Character CL2 Design Quality CL 3 Heritage Assest Conservation Areas and Historic Spaces CL5 Living Conditions CL Small-scale Alterations and Additions CL 8 Existing Buildings Roof Alterations / Additional Storeys CL11 Views CE 6 Noise and Vibration The council will require all development to respect the existing context, character and appearance, taking opportunities available to improve the quality and character of buildings and the area and the way it functions (from CL 1) The design proposal for the Interactive Gallery responds sensitively to the existing architecture of the Science Museum building. The design approach from the outset has been to preserve and enhance the existing architecture and character of the building, and to use the existing features as a frame of reference for additions to the space. Resist the change of use of any building (from CL3) Requirements for development to be: a.i. Functional fit for purpose; a.ii. Robust; a.iii. Attractive; a.v. Sustainable; a.vi. Inclusive (from CL2) The Gallery space retains the existing and historic use of the space as a Childrens Gallery. It provides a fully accessible Gallery space with accessible exhibits and WC provisions for school groups and the general public. Later alterations to the original architecture, infilling the courtyards and covering the atrium combined with the difficulties of opening the high level windows throughout the Gallery space have made it difficult to naturally ventilate the space. In order to improve the quality of the environment for users, both now and in the future the new ventilation system will improve this, helping to make the space a more comfortable environment. The passive ventilation will also improve the sustainability of the Gallery space, which will no longer rely on air conditioning. Preserve and enhance the appearance of the conservation area (from CL3) Resist additional storey and roof level alterations on buildings that have a roof structure or form of historic or architectural interest (from CL8) Protect and enhance views (from CL11) Whilst the reinforced concrete structure and roof of the third floor is of architectural significance the alterations to the Gallery and the peripheral spaces have also reduced the quality of the space, therefore reducing the architectural significance (from the Conservation Plan see appendix 1, page 45), and also the environmental quality. The ventilation strategy requires the ventilation cowls to be located on the existing roof, making a total of 9 openings (approx.. 1290mm x 1290mm) through the original reinforced concrete structure. At roof level the impact is minimal due to the amount of building services which are already located on the roof, the north court infill construction which has two additional storeys above the roof level and also the additional roof cover to the atrium (or Energy Hall). The height of the cowls is not greater than these other constructions or services (ventilation, PV panels, aerials etc.). There is also a relatively high parapet wall that obscures the view of the cowls to the surrounding area and buildings. The replacement of the existing high level windows and roof lights is also less significant. We think that these windows have been fitted at a later date, they do not appear to be original. They are not particularly notable or attractive windows: a mixture of metal frame (possibly aluminum) single and double glazed windows, which are not currently performing very well. We feel that the replacement of these will not only improve on their performance but also their appearance. Interactive Gallery 25
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8 APPENDIX Appendix 1. Conservation Plan Prepared for SMG, June 2013 by Alan Baxter Interactive Gallery 27