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Designing homes for the 21st century: lessons for low energy design (NF50)

Overview

There are many challenges in designing homes fit for the 21st century. We need homes that achieve zero carbon performance, whilst providing a healthy indoor environment. We also need homes that are resilient to climate change and are not susceptible to overheating for extended periods during the year.

To meet these challenges, this guide argues for an integrated design approach fully informed by the needs of home occupants, and proposes a model for planning new homes in four stages: evaluation, best practice, integration and optimisation. Overall the author advocates a ‘fabric first’ approach, making sure that insulation, air-tightness and ventilation are designed to give the best practical performance before low carbon technologies are applied.

Summary of content

The home-building industry is undergoing unprecedented change and it seems likely that the future home will include more technology than ever before, presenting challenges for construction and operation.  Even now, there are concerns that the homes we are building today are difficult to maintain and operate; that technology may not be delivering to its full potential and that, in the drive to conserve energy, we may be inadvertently inviting other problems such as overheating and poor indoor air quality.  Current design and procurement practices may need to change if these issues are to be addressed and this has implications for designers, developers and importantly for the end users, the people who have to live in, and operate, the home.

Much of the guidance that has been produced to support the industry has focused on targets and outcomes with little regard for process.  This brief overview describes the processes and decisions that should be made to arrive at a robust and functional low energy design. It identifies dependencies between the passive aspects of the home (the fabric of the external walls, the insulation and immovable parts) and the active systems (services, ventilation and heating).  It encourages designers to understand that these two aspects have to be planned for concurrently, and the effectiveness of each is highly dependent on the other.

The aim of the guide is to promote a better understanding of the ‘whole’ without getting drawn into the detail of technological solutions or the regulations they serve.  In the guide we have placed a lot of emphasis on the design of effective ventilation, anticipating the widespread use of mechanical ventilation which is becoming a common feature of very highly insulated and airtight homes.

The guide is divided into four sections corresponding to a logical sequence of steps that ought to underpin the design process.  Starting from the very first decisions that need to be made at a planning stage, the guide illustrates practical examples to promote a better understanding of the essential elements of a low energy design.

In the last section, we look at ways of providing heat and hot water to the home and briefly explain the challenges presented by low and zero carbon technologies.  This is not a comprehensive survey of all the technologies available but it does identify common issues for the design, installation, commissioning and operation of the systems.