Product specification is the key to sustainable social housing

The recent Government announcement confirming the need to create more than three million new houses by 2020 has galvanised the construction industry to focus how to meet this challenge. A large proportion of these proposed new properties will be aimed at relieving pressure on the social housing sector, so the process of identifying the products that meet the necessary legislation to construct these homes has never been so important.

When it comes to product selection, there are now more factors to consider than ever before. Issues like climate change, energy efficiency, changing social and environmental factors, as well as the introduction of the Code for Sustainable Homes, mean that staying on top of the sustainability agenda will play an increasingly important part in shaping the UK’s homes of the future.

Together, these issues have combined to create unique challenges for architects and specifiers working in the public sector, who must now reassess the way they create buildings and take more positive steps towards specifying high quality, sustainable building materials.

Tackling the challenge of climate change

As the recent bad weather has demonstrated, adapting to climate change will to be one of the major drivers in the design and build of new homes. Rising summer temperatures, more extreme weather conditions, and potentially harsher winters will have a significant and lasting impact on the way we will live and work. Specifying products that are capable of creating buildings that can withstand the effects of climate change therefore has to be a priority for everyone involved in construction.

One has only to look at the CIBSE TM36* report ‘Climate change and the indoor environment: impacts and adaptation’ - which shows that the number of days that outside temperature will exceed 25 degrees Celsius will double by 2040, and triple by 2080 - to understand the true scale of climate change. As these predictions neatly show, it is cooling, as well as heating a building, that will become more of an issue in the coming decades.

Chartered Institute of Building Service Engineers TM36 report

The importance of a building’s thermal performance has therefore rightly been highlighted by the recent introduction of stringent new amendments to Part L of the Building Regulations. In addition to specifying levels of thermal efficiency, Part L also highlights the risk of overheating due to increasingly better insulated and airtight buildings. Unquestionably, the thermal mass of a building will play an important role in the future of energy efficient house design by regulating internal temperature fluctuations and will be instrumental in meeting the challenge to construct zero carbon homes by the Government’s 2016 deadline. The amount of thermal mass used in floors and walls will contribute significantly to the amount of energy used in heating and air conditioning, and the associated CO2 emissions as well as future-proofing our homes against climate change.

And as the recent floods have also shown, with the Government stating that more houses will be built in flood plain areas, it is essential that properties are built from products that are able to withstand multiple flood events, without sustaining long term structural damage or succumbing to damp and rot. Concrete blocks offer a reliable and sustainable option for developers building in flood plain areas, as they are able to endure immersion in water with no long-term damage.

Product innovation – back to basics

Because walls make up the largest surface area of a building, ensuring that walling products have high thermal mass and low U-Values is extremely important. For example, concrete structures have high thermal mass potential, particularly if blocks are used to construct internal partitions as well as external walls. This is because concrete blockwork retains and regulates heat much better than timber and steel frame alternatives. In fact, the innovative use of concrete blocks from Tarmac Topblock in carbon zero housing projects has already allowed developers to build properties that deliver significantly reduced energy consumption such as the Honingham Earth Sheltered Housing Scheme in Norfolk.

Concrete blocks are also playing an important part in the revival of solid wall construction, a building technique that has perhaps been overlooked in the past. By combining the benefits of Durox thin joint blockwork - a proven modern method of construction - with new external renders and cladding systems, Durox solid wall construction gives specifiers access to a total building solution. It also removes restrictions on the height of walls that can be built in a day, and as a modern construction method, delivers reduced build times, simplicity of construction and improved health and safety benefits.

In practical terms, Durox solid wall combined with an external insulating render negates the need for additional internal insulation, and the relative position of the blockwork and the render help to maximise the thermal mass potential of the structure. This also cuts down on the quantity of materials needed and the associated environmental costs of producing and transporting these materials to site. The use of Durox solid wall creates a ‘tea cosy’ effect, which means the wall is capable of achieving U-Values as low as 0.15W/m2K, as well as retaining the heat for longer periods with a wall thickness of just 340mm. It also helps to reduce the risk of interstitial condensation and the simple nature of the walls construction means that only a thin coat of internal plaster is required, further reducing the material costs and environmental impact.

It is the tried-and-tested nature, as well as the innovative use of these new products and construction methods that make them so appealing to the social housing sector. This is important to remember, as all building methods should be focused on balancing the long term energy-efficiency, sustainability, cost and overall aesthetic appeal of new-build properties, with end-user satisfaction.

Whole-life impact

Whatever the method of construction, to assess the true sustainability credentials of a building, it’s important to take into consideration the whole-life environmental impact of the building products specified. This means looking at not just the embodied energy that it takes to extract, process, transport and install the product, but also the impact that the product ultimately has on the long-term operational and environmental efficiency of a building. Relating this principle to block construction, research from the Concrete Centre shows that over a 60-year period, a concrete or masonry constructed property will emit around 15 tonnes less CO2 than a timber-framed alternative.

Future flexibility

But creating sustainable buildings is about more than our changing climate and carbon emissions. In the UK, escalating house prices are placing increasing pressure families and children to stay in the same house for longer, rather than moving out or financing a move to a larger property. This means that in the future, we’re likely to see more people opting to extend or convert properties to accommodate a greater number of individuals. Therefore, it is essential to ensure that new-build homes use products like Topblock concrete blocks that offer real flexibility so that homes can be expanded easily.

Concrete blocks enable the easy removal or replacement of parts of a building, so if home owners want to extend rooms to add space for an expanding family - or even go greener, by installing a wind turbine - having a property constructed with blocks will not only reduce future construction and renovation costs, it ultimately offers more choice.

It’s also essential that local authorities consider whether a product is fit for purpose. It’s no good if housing has to be torn down after 50 years because the materials used in the first place were chosen on a cost basis, or on short term benefits. Ultimately, this has far worse impact on the environment and is certainly not a sustainable option in the long term.

Sustainable building products need to offer durability and longevity – and Topblock’s range of concrete blocks score highly on both counts. Block built properties can last for hundreds of years and concrete also has great soundproofing qualities - a big plus when we’re likely to be living in much closer proximity to our neighbours in years to come. It’s also very safe. Concrete is non-combustible, and its thermal mass means that in the event of a fire, blocks can absorb heat, thus acting as a fire barrier and giving people vital extra minutes to evacuate.

In addition to all these benefits it is worth noting that concrete is 100 per cent recyclable. So when a building made with concrete blocks comes to the end of its life, the material can be crushed and recycled - perhaps even used to make new blocks. In fact, our Hemelite blocks can contain up to 80 per cent recycled content. In this way, we can help protect a finite resource and contribute to the future sourcing of sustainable raw materials.

The one certainty is that with future climate change and a rising demand for new housing, concrete blocks will to play an increasingly integral role in building a more sustainable future.

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Fact 39

The advantage of a new build home is that every measure can be taken to improve the energy efficiency of your house. The energy used in homes accounts for 48% of Britain's greenhouse gas emissions. Source: Self Build ABC