Nature has provided humankind with food, fuel, and shelter throughout evolutionary history. However, in contemporary cities, many natural landscapes have become degraded and replaced with impermeable hard surfaces (e.g., roads, paving, car parks and buildings). The reversal of this trend is dynamic, complex and still in its infancy. There are many facets of urban greening initiatives involving multiple benefits, sensitivities and limitations. The aim of this paper is to develop a characterisation method of nature based solutions for designing and retrofitting in the built environment, and to facilitate knowledge transfer between disciplines and for design optimisation. Based on a review of the literature across disciplines, key characteristics could be organised into four groups: policy and community initiatives, multiple benefits assessment, topology, and design options. Challenges and opportunities for developing a characterisation framework to improve the use of nature based solutions in the built environment are discussed.

Urban man-made assets have impacts not just on those who develop, build and operate them, but on people who may be quite remote from them. For example, the impact of a building on greenhouse gas emissions arising from fossil fuel use, pollution caused by travel to work patterns and employment opportunities provided by urban developments may be far removed from their immediate locality. There is a growing recognition of the need to internalize these external costs and benefits in accountancy frameworks, drawing on experiences in accounting for sustainable development. This desire, however, presents major challenges in identifying, evaluating and allocating the external environmental, social and economic costs and benefits of an urban environment. This paper reports on the development of an Urban Development Sustainability Assessment Model (UD-SAM) which allows decision makers to identify sustainability indicators (economic, environmental and social) and which may lead to more holistic evaluation of the sustainability impact of elements of the urban environment. The UD-SAM builds on a sustainability assessment model (SAM) developed originally in the oil industry. This paper describes how SAM has been tailored for the construction industry and urban sustainability assessment, and how a set of generic sustainable development indicators have been identified and validated by stakeholders.

A number of innovations in building envelope technologies have been implemented recently, for example, to improve insulation and air tightness to reduce energy consumption. However, growing concern over the embodied energy and carbon as well as resource depletion, is beginning to impact on the design and implementation of existing and novel building envelope technologies. Biomimicry is proposed as one approach to create buildings which are resilient to a changing climate, embedded in wider ecological systems, energy efficient and waste free. However, the diversity of form and function in biological organisms and therefore potential applications for biomimicry, requires a holistic approach spanning biology, materials science and architecture. It is considered timely to re-examine opportunities to learn from nature, including in the light of recent understanding of how plant form and function are determined at the cellular levels. In this article, we call for a systemic approach for the development of innovative biological and living building envelopes. Plant cell walls are compared to building envelopes. Key features of cell walls with the potential to inform the development of design principles of biological and living building envelopes are identified and discussed.