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There is a lot to weigh up in choosing to renovate a house or build from scratch. These are some of the main considerations when it comes to renovating or building to create a cost-effective sustainable home with as minimal impact as possible.
The strengths and weaknesses of an existing building need to be considered in deciding whether to renovate or build new. Questions to ask include: What is the quality of construction? How have the materials aged? How does the existing building perform in terms of thermal efficiency, natural light and ventilation? Does it have inherent character, like a heritage façade or other unique details, that can or (depending on the council's guidelines) must be preserved?
For any renovation, an architect will determine what can be reused and what must be replaced, and what specific architectural challenges a renovation poses in order to meet a client’s brief. For a sustainable house, these decisions will be influenced by the embodied carbon and cost of the renovation, and the energy efficiency that could be achieved using existing structures and materials. Where possible, sustainable architecture will seek to reduce embodied energy and waste by retaining and reusing existing materials, while adapting the house to minimise the environmental footprint of its operation.
Renovating reduces the embodied energy of a building by extending its life. By minimising demolition and/or construction, it reduces the overall environmental impact and waste of materials.
Renovating can be (but is not always) more affordable than building new, and it can preserve the sentimental value of a house and its contribution to the streetscape. Reglazing, recladding and alterations to the openings and spaces of a building will make it more energy efficient and thermally comfortable. Integrating renewable-energy technology will reduce energy consumption and carbon emissions.
Building from scratch provides a clean slate for designing a house with energy efficiency at its core. Individual needs and desires are not hindered by existing conditions: a fresh start affords greater creative flexibility to realise the ‘dream home’. Investing in passive design and modern, durable, high-performance materials will result in lower operational costs.
The construction of a new house will have a greater initial impact on the local environment, especially if excavation disturbs the natural state of a site. New constructions also have higher embodied energy as they require new materials. However, by using recycled and/or recyclable materials the impact of new builds can be somewhat mitigated.