The built environment — and buildings in particular — are major carbon emission sources that must cut to near zero by 2050. New buildings can be designed for energy efficiency. However, Jon Herbert points out, the UK’s legacy of millions of existing properties that will still be standing mid-century cannot be ignored.

How long will buildings that are being designed and constructed today last? Technologies and trends change. Development and re-development is a constant process. However, it is not inconceivable that some of the world’s largest and boldest structures could continue to function for centuries to come.

Modern, high-performance buildings like skyscrapers are designed and built to withstand extreme environmental loads such as earthquakes, severe wind and water, that statistically only result in catastrophic failure events once every 500–1000 years.

In a shorter time frame, a major challenge is learning how to live energy efficiently and sustainably with ageing architecture originally meant for lifespans and environmental conditions quite different from today’s. But technical advances are making the impossible possible.

Old and beautiful

The UK, with low levels of demolition and new construction, is estimated to host some of Europe’s oldest housing stock. It is highly likely that 70–80% of today’s buildings will still be around in 2050, the date by which Britain is committed under the UK Climate Change Act 2008 to have cut emissions by 80%. The built environment accounts for almost 50% of UK carbon.

Contemporary lifestyles are changing. Yet on average, British people still spend some 90% of their time indoors. Most British houses were built before the introduction of energy performance regulations. Consequently, they are notoriously energy inefficient and leaky. The upshot is that through electricity, gas, oil and solid fuel use, they account for roughly 25% of the UK’s carbon footprint.

A parallel crisis is energy affordability; combined energy and damp issues are said to be responsible not only for fuel poverty, but also respiratory, rheumatic, and even anxiety and depression problems. The UK also has one of Europe’s highest rates for so-called excess winter deaths: winter fatality rates above all-year-round norms.

Starting over

The easiest way to become more cost and energy efficient might be to knock down existing buildings and erect brand-new ones, but for obvious reasons this is not going to happen. A viable alternative is to retrofit existing structures to higher standards.

While homes are an obvious target, commercial buildings offer large upgrading opportunities that produce associated environmental gains, despite half a million UK buildings being officially listed with constricted scope for performance improvements.

Internal and external insulation, airtight window frames, double and triple glazing, and even airtight outer shells are all part of possible solutions. In tandem, EU appliance regulations continue to push down energy needs.

Because money spent on retrofitting reduces energy costs, it is generally seen as investment rather than consumption. Improvements in comfort are also seen by many building owners and tenants as marketable advantages. Rolling retrofitted energy efficiency measures into new kitchen and bathroom packages can add to the attraction and value of building stock. This is also an opportunity to upgrade access, health and safety, and security.

However, climate change is the dominant driver for zero-carbon building.

UK challenge

At present, the UK has some 26 million homes, and almost two million non-domestic commercial and public buildings that add to the national carbon footprint. To halve greenhouse gas emissions by the interim target date of 2027, renovation, retrofitting and refurbishing old buildings must be achieved on a large scale.

Homes are important but some 18% of UK carbon emissions come from non-domestic buildings. By 2050, the Building Research Establishment calculates that 60% of these will be more than 40 years old. The Carbon Trust estimates that cutting 2005 level carbon dioxide (CO₂) emissions by 35% could save the UK £4.5 billion by 2020.

Digital technology is a new starting point. Historically, buildings have been fitted with energy meters that measure overall consumption. Submeters now allow energy use per floor, per department, per production line and per individual piece of equipment to be monitored, recorded and analysed in real time.

Digitisation in fact goes further. Energy use can now be co-ordinated with the number of people occupying or working in a building at a particular time, switching utilities on and off according to when they arrive or leave.

Obvious starting points are heating, lighting and ventilation, which are calculated to account for 46%, 23% and 11% of carbon emissions. Old boilers replaced by more efficient modern units may be a first step. However, a problem frequently overlooked when older buildings are updated in stages is potential conflicts between heating and air-conditioning systems that are not aligned. Time-based controls help but complete integration is usually more successful.

One other energy reduction innovation is variable speed ventilation fan motors that respond either to CO₂ or detected occupancy levels. Heat recovery systems can enhance this. But one overriding and often missing element in closing the gap between theoretical and actual practical performance is the human factor.

Let there be sustainable light

The UN predicts that the global population will reach a resource-hungry 10 billion by 2050; more than 6.5 billion are expected to live in modern cities of the future that have yet to be designed, built and/or radically upgraded. Another observation is that if the present increase in the rate of energy efficiency were to rise from its current 1.5% annual level to 3%, that might actually be enough to meet some two-thirds of the ambitious carbon reduction targets set at COP21 in Paris at the close of 2015.

Again, digitisation and smart energy systems that share data and information between components could be key.

One focus is lighting. Here, it is estimated that the number of light points could grow to 60 billion in the next decade or so. With the demise of incandescent bulbs, LEDs could halve energy use. More than that, the potential for smart reactive lighting, both within buildings and in the outdoor environment of smart cities, could see energy demand drop by as much as 80%. If supplied by renewables, this opens the door to the cost-efficient concept of “light as a service”.

Philips is a leader in this field and sees the transition to connected lighting products, systems and services as fundamental to how people of the near future live, work, relax, grow crops, and build and power communities.

It says lighting has accounted for some 15% of global electricity use but foresees this falling close to 8% by 2030. Meeting energy efficiency targets depends on ambitious programmes to provide sustainable buildings. A recent estimation of building renovation rates is 1.2%. If the policies, building codes and procurement criteria were put in place to lift this to 3%, something more sustainable could be achieved, the Amsterdam-based company believes.

Again, there could be potential gains in more than just costs for owners if funding was leveraged over a building’s lifespan. Not only could an estimated €270 billion be saved in energy costs, 1400Mt of CO₂ could be taken out of the environment; roughly equivalent to closing some 1250 power stations. One suggestion is that an obvious transition point could be when buildings change hands.

Back to the future

• Most of the UK’s existing buildings and housing stock will remain functional far into the future.
• Energy efficiency and sustainability can be improved continuously throughout their extended lifespan and help to meet the UK’s demanding 2050 carbon reduction targets.
• There are major potential benefits for both owners and occupiers.
• Heating, lighting and ventilation services are effective starting points.
• Digital technology and smart systems can also create new commercial opportunities.

Published by Croneri on 19 June 2018