The latest concrete constructed home from Pure Design features polished concrete floors and honed grey masonry block feature walls - all from Firth.
Concrete has been in the firing line recently due to the energy consumed in its production - mainly cement production, the 'glue' in concrete. So how does this impact on residential construction? Should we continue to build houses from this much maligned - yet misunderstood - product?
'Concrete' accounts for approximately *8% of the worlds CO² emissions - that's for all concrete construction worldwide. To put this into perspective, 'Agriculture' accounts for 12% and the 'Automotive Transport Industry' 15%. "We could save the planet faster by becoming vegan and walking everywhere... rather than building less durable houses", says Grant Watson, Director of Pure Design Ltd, an advocate of residential concrete construction and a long-time customer of Firth. "But there is far more to the story."
Durability
"Using concrete for residential home construction provides durable weather resistant structures that are longer lived and generally require less maintenance than alternative construction methods within the industry," says Grant. "For example, the Parthenon is almost 2000 years old and is made with a very rudimentary form of Roman Portland cement concrete and bricks."
Grant argues that to put that in perspective, the oldest building in New Zealand, made of timber frame and cladding, is NZ Government House at 143 years old. "It is only one tenth of the age of the Parthenon. If one did an analysis of the maintenance costs of the two buildings over their life span and then divided that by their age to get an annual cost, the concrete structure is far more economically viable and energy efficient. So, we need to calculate the energy impact of a building, not only for its embodied energy, but the ongoing energy consumption due to maintenance and energy usage during its lifetime. As concrete structures tend to have longer life spans, this aspect becomes even more relevant and important when deciding what the best solution is for ourselves, our customers and the planet."
"As an aside, I am certain that the concrete we use now far excels the concrete used by the Romans 2000 years ago, so it is anyone's guess how long these current structures will endure. And whatever that is it will well exceed the 15-year life span required by law under the current New Zealand Building Code that some consented approved NZ buildings currently fail to achieve, which in itself is just shameful."
Energy use
"Concrete buildings are generally far denser and heavier in mass compared to other forms of construction. A by-product of that physical mass is the ability to support passive solar design, with well-designed buildings using proven passive solar solutions. This produces buildings that are naturally warmer in winter and cooler in summer, without the need for additional heat pumps and other forms of energy consuming interior environmental controls."
If additional temperature and interior climate control is desired, outside the natural range, concrete also allows the use of hydronic forms of heating and cooling, either from solar or thermodynamic energy sources running within the concrete itself, while using the mass to amplify the energy storage abilities of the concrete form and radiating that to the interior environment. This provides the building's users with a more pure form of environmentally friendly heating/cooling energy... if it is well designed to take advantage of this denser material."
Recycling
"The early phases of many construction projects involves the demolition of concrete foundations, sidewalks, driveways and structures which can leave contractors, such as ourselves, with a sizable volume of heavy, dense material to deal with. Fortunately, we can recycle concrete and reuse in many ways.
Reusing concrete can be a good way to reduce construction costs while providing some benefits to the environment. Recycled concrete not only stays out of landfills, but it also replaces other materials such as gravel that must otherwise be mined and transported for use."
Design
"As concrete is delivered to us in liquid form it allows us to pour it into any mould and it is extremely flexible in creating endless shapes and forms in a cohesive and seamless way that no other material can do. This allows for limitless design ideas and philosophies to be imagined, formed, implemented and cast. When cured this shape/form is locked in, resulting in a rigid structural sculptural form of architecture.
Just look at the work of one of my favourite architects - John Lautner, his Sheats Goldstein house (1963), the Elrod House (1968) or Mabrissa House (1973) - to see what can be achieved with this material for residential construction when thought is given to its unique properties and attributes.
The possibilities are endless, and the results are enduring and unachievable with any other current building medium in the construction industry. Each piece of concrete ever poured is like no other and will age like no other. The Japanese call this 'Wabi-Sabi'. Characteristics of the wabi-sabi aesthetic include asymmetry, roughness, simplicity, economy, austerity, modesty, intimacy and appreciation of the ingenious integrity of natural objects and processes as they age... and this is a beautiful thing."
Speed
"Concrete, especially precast concrete, is supplied and erected very quickly and it is not unheard of to see houses have all their walls erected in one day. This is why concrete is a preferred option for commercial buildings. Residential building is no different. In residential apartments, the speed, acoustic resistance and fire resistance of the panels are the primary driver to quality living environments."
"As you can see, I am an absolute advocate of the use of concrete in residential construction," adds Grant. "I hope when you design your next house you will keep an open mind."
*Carbon emission percentages have been taken from the Carbon Brief website: www.carbonbrief.org