The changing climate of the Earth is already affecting our buildings. In Ireland, we will have wetter but warmer winters and drier summers. Intense bursts of heavy rainfall will become more frequent, and there will be more flooding as a result. So how are architects and builders responding to these challenges?
Of course, people are already thinking about making houses more energy efficient, but there are other considerations the industry has been slower to take on board. For instance, there will have to be systems to actually cool building in summer, and finding a way to do that which does not involve CO2 emissions will be a challenge.
The materials used will have to be energy efficient, of course, but will also have to deal with more extreme conditions. Builders will have to pay attention to detailing on buildings and how materials behave in different temperature conditions.
Managing water will be a big issue for the construction industry – both in dealing with too much, too little, and the reaction of the soil to both of these extremes.
It is generally accepted that there will have to be a deep retrofit of existing housing stock to meet Ireland’s obligations under various international climate change treaties and agreements. Different parts of a building have different “life expectancies” – foundations won’t change, but cladding, roofing and glazing will also change several times in the lifetime of a standard house. These “intervention opportunities” must be exploited to adapt buildings at the least cost.
In terms of temperature, 24C is accepted as a “comfortable” temperature in a domestic dwelling. People start to feel uncomfortably hot at 28C and at 37C heat stroke starts to occur as the body cannot cool quickly enough and is unable to maintain its core temperature.
In a climate changed world, we’re going to have to look at the main principles of the passivhaus system:
- have a large thermal mass (a heavy concrete wall, perhaps, or a column) that will absorb heat during the day and release it at night,
- examine systems for the exclusion of solar gain
- airtight construction to exclude outside hot air
- high levels of insulation to minimise heat gain through fabric of building.
In other words, as summer temperatures climb (and the recent Paris climate change conference accepted that a rise of 2C was more or less inevitable now), shading of buildings is going to become very important.
Ironically, all the measures we in Ireland are undertaking to keep heat INSIDE our homes will now serve the opposite purpose of keeping heat OUTSIDE. (See the UK government’s 2005 publication Beating the Heat).
In addition, most houses will have to have some sort of active cooling system – air conditioning, in other words. We will have to have:
- shading systems for buildings
- glass that excludes solar gain (see Low-E-Plus Solar Control for details)
- reflective building materials that reflect rather than absorb heat
- cooling systems powered by domestic scale renewables or groundwater
It may also be the case that mechanical heat recovery systems will be redundant in a warmer world. The energy they expend may outstrip the energy they save.
When it comes to construction, the following considerations will have to be taken into account:
- changing rainfall patterns may increase shrinkage of clay soils
- foundations will have to perform better and last longer
- underground pipework may be affected by climate change
- slopes and restraining structures (banks, earthworks, ramparts etc) may become less stable
Climate change also brings more wind – and the wind load on buildings will have to become a major construction factor. Older buildings will be more vulnerable to wind damage.
In terms of detailing, there will have to be more recessed window and door reveals, more projecting cills with drips and more render finishes (as opposed to exposed brick).
Rainwater or grey water harvesting systems will become the norm, we will have gutter and downpipes with greater capacity, and, most worrying of all, our sewers may not function properly as we use less water. Furthermore, architects and builders will have to consider the dangers of flash flooding as intensive rainfall events become more common.
- Source: UK Technology Strategy Board: Design for future climate – opportunities for adaptation in the built environment: http://www.arcc-network.org.uk/wp-content/D4FC/01_Design-for-Future-Climate-Bill-Gething-report.pdf