Urban heat refers to the higher temperatures experienced in urban areas. Little vegetation or evaporation, and increased impermeable vertical and horizonal surfaces cause urban areas to be warmer than surrounding rural and natural areas. This is further exacerbated in inland areas that can be up to 5% warmer than coastal areas.

Changes in land-use patterns influence micro-climates. This is especially true for the areas where increased horizontal impermeable surfaces such as concrete and asphalt can absorb solar radiation and reduce heat reflectivity.  Similarly, increased hard vertical surfaces such as building facades and roofs can reflect heat to surrounds and to the city below. Increased prevalence of air conditioning system outlets on the sides of buildings further increases temperatures and exacerbates UHI micro-climates.

Along with regional climate influences, the degree of micro-climate fluctuation is dependent on a range of factors including green space and urban forest coverage. Green infrastructure can play a key role in mitigating the urban heat island effect to create cooler spaces, reduce demand for electricity, insulate buildings, support water absorption and control air movement. Green infrastructure has myriad benefits for ecosystems, soil, air, and water health, community health and wellbeing, and the economy.

The urban forest comprises trees, shrubs, plants, and other vegetation in the city on public and private land. The urban forest includes vegetation in and along streets, parks, gardens, activity centres, waterways, wetlands, coastal areas, car parks community gardens, and green built fabric such as green walls and roofs. There are other requirements in DCP 2023 relevant to meeting urban heat objectives. These are in relation to landscape areas (including deep soil areas), trees (including tree protection, compensatory trees and requirements for new trees and water sensitive urban design.

The National Construction Code and State policies regulate key aspects of building design.

Homes that adopt passive design minimise their impact on their surrounding environment by reducing energy requirements in heating and cooling and by minimising their contribution to the external environment through excess heat loss/ heat production generated by mechanical cooling systems (the exhaust from an air-conditioner unit).

High passive thermal performance of buildings with reduced reliance on air conditioning to maintain comfortable and safe indoor conditions is the desired outcome for all buildings.

This section applies to all development.

For development involving heritage items or heritage conservation areas identified under Newcastle Local Environmental Plan 2012 (LEP 2012), a merit assessment will be required to ensure the outcomes sought are balanced with heritage conservation outcomes.

The following sections will also apply to development:

• C3 Vegetation preservation and care
• C4 Stormwater
• C12 Open Space and landscaping

1. Design built form, including public and private open spaces, with measures that reduce the impact of high to extreme heat stress days on residents, workers and visitors.
2. Reduce and mitigate the contribution of built development to urban heat, through passive design and nature-based solutions.
3. Mitigate urban heat to facilitate a high level of comfort throughout the year, with improved outcomes on hot days and the summer period.
4. Encourage landscaping and shading that supports urban heat resilience.

A word or expression has the same meaning as it has in the LEP 2012, unless otherwise defined. Other words and expressions include:

• Albedo - is the fraction of solar radiation reflected from a material’s surface.
  
  
• Green infrastructure – is the network of green spaces including built fabric and urban forest. It supports sustainable communities and is strategically planned, designed and managed to support a good quality of life in the urban environment.
  
  
• Heat rejection unit – is a mechanical cooling unit or system that rejects excess heat when the cooling unit or system heat load is reached.
  
  
• Hot days - Defined by the Climate Council as days between 30°C and 35°C.
  
  
• Maximum external solar reflectance – is the maximum allowable percentage of solar reflectance for the external face of a Reflective Surface. The percentage of solar reflectance is to be measured at a normal angle of incidence.
  
  
• Non-reflective surfaces – are those surfaces that diffusely reflect light and heat and have surfaces that have specular normal reflection of less than 5%.
  
  
• Reflective surface ratio (RSR) – is the ratio of reflective to non-reflective external surface on any given facade. Reflective surfaces are those surfaces that directly reflect light and heat and have surfaces that have specular normal reflection of greater than 5% and includes, but is not limited to, glazing, glass faced spandrel panel, some metal finishes and high gloss finishes.

• Reflective surfaces – are those surfaces that directly reflect light and heat and have surfaces that have specular normal reflection of greater than 5% and includes glazing, glass faced spandrel panel, some metal finishes and high gloss finishes.
  
  
• Solar access – is the ability of a building to continue to receive direct sunlight without obstruction from other buildings or impediments, not including trees.
  
  
• Solar reflectance index (SRI) – is a composite measure of a materials ability to reflect solar radiation (solar reflectance) and emit heat which has been absorbed by the material. For example, standard black paint has a SRI value of 5 and a standard white paint has a SRI value of 100.
  
  
• Thermal comfort - The condition of mind that expresses satisfaction with the thermal environment; i.e. the conditions in which a person feels neither too cold nor too warm.
  
  
• Urban heat - A general term that refers to high temperatures in urban areas that pose a risk to our communities and infrastructure.
  
  
• Urban heat island effect - is the tendency of cities to be much warmer than their rural counterparts. Urban surfaces such as roads and roofs absorb, hold, and re-radiate heat; raising the temperature in our urban areas. Human activities such as traffic, industry, and electricity usage also generate heat that adds to the urban heat island effect.
  
  
• Wintergardens – are balconies that have an additional layer of operable glass, that can be readily enclosed and does not compromise access to daylight.

Objectives

1. Reduce the contribution of development to urban heat reflected from facades in the Newcastle city centre, Wickham, Renewal corridors and Local centres
2. Minimise the reflection of solar heat downward from the building facade into private open space and/or the public domain.

Figure B6.01: How shading reduces solar reflectance. Image courtesy of WSROC Urban Heat Planning Toolkit, 2021