1.85 The selection and arrangement of materials should follow a clear strategy determined by the proposal’s response to context, programme and form.

1.86 To ensure the quality of materials and details at completion, large scale drawings and material samples should be provided at planning application stage and secured by condition. See Fig.29 for typical submission requirements.

1.87 Where the architectural expression of a building is reliant on subtle articulation of materiality or depth of the facade, typical bay studies should be developed at pre- application stage and included in the planning submission drawings - see Fig.29.

1.88 The details of a building should create sufficient depth in the facade suitable to the chosen material. For predominately brick buildings, for example, window and door reveals should generally be more than 1.5 standard brick depth to create sufficient depth in the facade.

1.89 Details should typically be provided at 1:50 or 1:20 scale on an appropriate paper size. Samples of materials as specified in Fig.29 should also be provided where necessary.

1.90 The choice of primary materials for both the public realm and buildings should be justified through their appropriateness to the site. Material choices consider the likely exposure to pollution and how the materials will weather.

1.91 For proposals that include works to the public realm, consideration must be given to the availability and ease of maintaining materials in the future, whether this is at private or public expense. In the case of the latter, a quantity of any special paving materials from the same batch may be required for this scenario.

1.92 Attention should be paid to parts of buildings and spaces where materials are directly experienced by users, such as entrances, windows, doors and balconies. Additional details as set out in Fig.29 may be required to ensure these elements are of suitable quality.

1.93 Private amenity spaces such as balconies and terraces should be well integrated within the overall design of the building using complementary materials and detailing.

1.94 The choice and application of materials should be informed by maintenance requirements. Glass balustrades, for example, should only be used where residents are able to easily clean these features and metalwork is therefore often preferred.

1.95 The strategic design approach refers to the approach to existing structures on the site, the form of construction and the specification of materials and systems.

1.96 Whole life carbon refers to the combination of operational carbon and embodied carbon of a proposal, including waste production. On all projects, circular economy principles should be considered from the outset to minimise waste from construction.

1.97 All development should follow the energy hierarchy (see Fig.30), with emphasis on the first point to “be lean” and use less energy by virtue of the design. Energy efficient buildings can minimise emissions as well as air pollution as they reduce the heat demand. Development in Bexley can approach this by using the following:

1. Development sites with existing buildings should explore ways that all or part of the existing structure can be retained and the energy efficiency improved.
2. New development should consider the embodied energy of different design and construction strategies. Construction methods that have low embodied carbon will be looked upon favourably.
3. The fabric first approach should be considered to ensure operational energy use is as low as possible

1.98 The second point refers to “be clean” or to use sustainable forms of operational energy. This can be achieved through the following:

1. Efficient electrical equipment such as LED lighting and smart/efficient appliances to reduce energy demand
2. Water resistors to reduce overall usage of water within taps and showers
3. Smart metering enables monitoring of energy use and feedback to encourage behaviour change

1.99 The final point in the energy hierarchy is to “be green” and use renewable energy:

1. Avoiding the installation of equipment that uses fossil fuels such as gas in favour of renewable energy such as air source heat pumps
2. Solar thermal energy can be used in tandem with other water heating systems to raise initial water temperature
3. PV panels are looked on favourable as on- site energy generation which can be stored locally or fed back into the electricity grid. See D24 on how to integrate these into the design of rooftops.

1.100 Assessment of design options against form factor, orientation and overshadowing is required to demonstrate applicants have followed the energy hierarchy and are compliant with London Plan Policy SI2.This assessment should be presented at pre- application stage.

1.101 Internal spaces must support the wellbeing of inhabitants through the provision of adequate levels of heat, space and light, mitigation of overheating, positive outlook, and the protection from detrimental air and noise pollution.

1.102 Development should follow the energy hierarchy as described in D13, the first priority of which is for proposals to reduce energy use and “be lean”.

1.103 Proposals should follow a fabric first and passive design approach as set out in Fig.32 to enable adaptation to climate change and ensure the comfort of inhabitants is prioritised at an early stage of design

1.104 Passivhaus certification is encouraged and looked upon favourably. As best practice, buildings should be designed to achieve the BREEAM or Passivhaus ratings as set out in the Local Plan Policy DP30 Mitigating climate change.

1.105 It is recognised that the composition of elevations following these parameters may differ from the prevailing context and should be justified through appropriate modelling and character analysis. This must be well resolved and follow other guidance within this document.

1.106 Residential development can follow the Overheating in New Homes guidance from Good Homes Alliance to ensure overheating risk is mitigated at an early stage of development.

1.107 Designs should demonstrate consideration for items typically affixed to proposals through submitting indicative plan and elevational locations of features such as those set out in Fig.33.

1.108 Whilst these elements are subject to detailed design, an indicative approach should be set out at application stage to demonstrate these can be appropriately accommodated within the design.

1.109 Applicants must account for whether the design of façades will result in building features overhanging beyond the boundary line, including objects attached to the facade. If the building line is close to the property line, then drawings of all items fixed to the facade such as gutters and pipes must be provided to ensure there are no overhanging features.

1.110 Where new development is proposed adjacent to flood defences, design features should not hinder access for certain plant and machinery required for flood defence repair, raising or replacement.

1.111 In locations with consistent building lines, private amenity spaces such as balconies should not overhang from the primary building line. Where the building line abuts the footpath, balconies should not overhang the public highway. In such locations recessed or “loggia” balconies are more appropriate as these also provide more privacy (see Fig.34).

1.112 Where a development includes windows within 1 metre of the boundary line, the windows should be fitted so that they cannot open over the boundary line.

1.113 Technical equipment on the roof of buildings should be considered early on in the design process. The height of this equipment, such as lift overruns, are included in the calculation of the overall height of buildings outlined in D07.

1.114 The appearance of equipment on rooftops should not be detrimental to the design of the building. Generally it should not be visible from the street or from points of higher ground level from which the proposal would typically be viewed.

1.115 If it is visible, the equipment should be incorporated into the design of the façade and massing and comprise materials that complement the façades. It should not disrupt the composition of the elevations as Fig.35.

1.116 Indoor air quality needs early consideration in building design. The location of ventilation inlets, flues, opening windows should be on higher floors away from potential sources of air pollution at ground level, and also removed from stationary plant at roof level or otherwise.

1.117 Applicants should take care not to locate flues and exhaust vents in close proximity to recreational areas such as roof terraces or gardens. These features should be incorporated into the design and not obstruct walkways, the visual setting or the installation of public amenities such as new bus stops.

1.118 Technical equipment should not affect the use of public spaces. The placement or relocation of objects such as junction boxes should be planned from an early stage in the design process. These features should be incorporated into the design and not obstruct walkways, the visual setting or the installation of public amenities such as bus stops.