The basic concept of sustainability is that the needs of the present must be met without compromising the ability of future generations to provide for themselves. However, population growth and dwindling resources mean that what is regarded as ‘sustainable’ today will almost certainly be regarded as insufficient tomorrow. Today we talk of sustainable buildings as minimising their negative impact on the planet; tomorrow we must start to think in terms of designing and constructing sustainable buildings to make a positive contribution to the planet.

In order to successfully achieve this, engineers should aim to: 

• better understand client drivers in order to advocate for shifts in approaches 

• re-examine what is human comfort and amenity 

• rethink our traditional linear use of resources towards a leaner, circular economy approach

• assure our supply chain to ensure safe, legal and socially responsible sourcing 

• better harness passive means, thus allowing the active interventions to be smaller and simpler

• apply whole-system thinking and seek strategies that offer multiple benefits, for example green infrastructure solutions 

In recognition of the changing demands on engineers, CIBSE has updated its Guide L: Sustainability to provide guidance on how building services engineers can most effectively respond to the evolving sustainability agenda.

As such, the document provides a focus on the areas of work where building services engineers have the greatest control and most influence on a construction project and the actions they should take to deliver sustainable outcomes. However, the document makes clear that this does not mean building services engineers should operate on their own nor that topics should be considered in isolation; it recommends that a holistic approach should be adopted, with “the use of whole system and whole life approaches wherever possible”. 

It is important to bear in mind when referencing this document that the Guide has been compiled not as a manual on how to design and build sustainably but more as a summary of current thinking and description of best practice on engineering sustainability design; as such the guide is structured to be both informative and to sign-post readers to more specific sources of information.

The guidance commences with an explanation of the overarching objectives of a sustainability agenda and summarises the main areas relevant to engineers. Topics are divided into those that engineers “can directly influence” and topics engineers “may be able to influence”.

Direct influence can be exerted on: operational performance, managing pollution, energy and CO2 emissions, health and wellbeing, materials and resource use, water use, and adapting to climate change.

Using the Health and Wellbeing chapter as an example, the guide outlines how building services engineers can contribute to ensuring the building can:

• Be designed to minimise pollutants and toxins

• Use passive approaches such as access to daylight, views out, natural ventilation, thermal mass, external shading, etc to enhance health and wellbeing and reduce the need for active systems

• Use natural materials

• Be enhanced by using active approaches, such as the colour temperature of lighting, mechanical ventilation and cooling to provide thermal comfort etc.

• Be further enhanced through collaborative working with designers and building operators to provide a low-stress environment that improves occupant health and wellbeing

• Provide the means to undertake regular integrated testing to verify that environmental conditions have been met.

Topics the guide says engineers may be able to influence include: ecology and biodiversity, local environment and community, recycling and waste management, flood risk, sustainable drainage and transport. As an example, the Ecology and biodiversity chapter outlines the following areas as those a building services engineer may be able to influence:

• Advocating the early appointment of an ecologist to carry out an assessment of the site and provide recommendations on protection, enhancement and management of biodiversity on the site (both in the design of the buildings and the landscaping elements) and if necessary or justified, mitigation.

• Giving special attention to assessing the impact on designated sites and protected species and taking into account the unavoidable climate change anticipated in the locality over the lifetime of the development.

• Promoting the use of planting, landscaping and living (green/brown) roofs and walls as part of the engineering strategy to help reduce cooling demands and improve the efficiency of photovoltaics

• Ensuring the engineering design is integrated with planting proposals, including for example the interaction of utilities with trees, and of drainage systems with ground and roof-level planting 

Engineers should be aware that the definition of a ‘sustainable building’ or ‘sustainable project’ evolves with knowledge and understanding of sustainability issues, and with practice. This Guide L provides overarching principles and guidance that can be applied on projects now to help develop building solutions for a new resource-constrained age.  

This is a sentiment encapsulated by Susan Home-Brookes, in the forward to the publication as: “Be informed, be committed, be bold, be creative, but above all remember your actions as an engineer are pivotal to the successful management of our home planet ecosystem, the safeguarding of all species (including humans) and the security and prosperity of our future generations.