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Manipulating metrics

Understanding precisely how much energy buildings use is the first step to reducing their carbon footprint. Giles Crosse examines United Nations Environment Programme (UNEP) moves to establish a global standard for doing so.

Today, UNEP estimates that the building sector is the single largest contributor to greenhouse gas emissions with about one third of global energy use taking place in offices and homes. Moreover, building-related CO2 emissions are set to rise from 8.6bnt in 2004 to 11.1bnt in 2020.

With this in mind, UNEP has introduced the Common Carbon Metric (CCM), developed by its Sustainable Buildings and Climate Initiative. The agency is hoping this could form the basis for a new international standard for measuring the environmental performance of existing buildings. The International Standards Organisation (ISO) is the world’s largest developer of such concepts, covering 162 countries. It is now looking at ways to develop new systems and methodologies to cover the global market using the CCM.

The CCM is intended to create a uniform system for defining the climate impact of buildings through a consistent protocol, which can, it is hoped, help develop international baselines for use by architects, designers and the construction industry.

In addition to potentially aiding global planning, creating new techniques for arresting energy use in buildings and new technology, the CCM could also support the formulation of carbon credit schemes and other emission reduction mechanisms. Working at governmental level, these can change the business playing field, opening the gates for renewables providers and low carbon technology developers to push in.

From a technical perspective, CCM is specifically designed to measure energy use when a building is operational. In other words, it is not applied to the construction phase. However, given that the day-to-day use of buildings accounts for 80% to 90% of their total energy consumption, the CCM deals with the period in a building’s lifespan where the greatest amount of emissions are produced.

First launched during the UN Climate Change Conference in Copenhagen in 2009, CCM describes both energy use and greenhouse gas emissions equivalent in buildings per metre squared or per occupant over the course of one year. It contains two approaches: a “top-down” model, which takes measurements from a collection of buildings or a “bottom-up” model, which is applied to an individual building.

After initial tests in 2010, the CCM has been further refined, and a second phase of testing has started recently, with preliminary results to be presented in October.

Professor Tomonari Yashiro, at the Institute of Industrial Sciences of the University of Tokyo, proposed the CCM to the International Organisation for Standardisation, and serves as convener of the working group that will prepare the draft standard.

“Sustainability related standardisation is one of the most significant issues in current ISO strategies,” Yashiro said. “There exist serious and urgent needs to establish international consensus on globally applicable common method of measuring operational energy use in existing buildings and to report the associated greenhouse gas emissions from such operations. I hope the standardisation by ISO will facilitate diffusion of CCM to many areas of business.”

True carbon usage

For CCM to work properly, it will need to address the key challenges in establishing true carbon usage of buildings. These are highly complex, and require detailed and meticulous carbon accounting. Arab Hoballah, Head of UNEP’s Sustainable Consumption and Production Branch, described the goals.

“Ideally, a complete accounting of the carbon emissions from buildings includes the full life cycle of buildings from construction through to demolition, taking into consideration the energy consumed and carbon generated to produce the building materials, the construction, operation of the building over its life span, and the demolition,” he begins.

“For existing buildings in a city, for example, built over many years, an accurate accounting for carbon emissions from construction is not practical. Additionally, in many instances, especially in developing countries, a lack of data or sophisticated means for accurate accounting constitutes a major constraint.”

Hoballah argues the CCM provides a tool and protocol that can be applied globally, as in almost all locations, data on energy consumption at the building level is available through utility bills or can be accessed through metering. By concentrating on the use stage of buildings, the CCM allows for collection and comparison of data across many countries. But alongside measurement, what are the top solutions, existing and future based, to reducing carbon usage in buildings?

“For new construction, applications of new technologies and innovation, designing buildings to incorporate renewable energy and time tested passive design techniques must be considered so as to avoid locking in inefficient energy consumption in buildings for decades to come,” he suggests.

“For existing buildings, retrofitting buildings for significant reductions in energy consumption can be achieved at low or no net cost using the savings from energy by applying existing technologies in areas of insulation, lighting, heating, ventilation and air conditioning.

“All countries should enact policies to promote low-carbon sustainable buildings. This can be done at national or municipal levels. Legislation can take the form of adoption of rating systems, mandating zero carbon buildings by a target date, enactment or enforcement of building and energy codes, incentives such as capital grants or public subsidies, and labelling, taxation on CO2 and public leadership programmes, including procurement standards for public buildings.”

Renewable help

This comprehensive list certainly illustrates what governments ought to be doing, but how might renewables themselves, or elements like microgeneration help in these efforts?

“Certainly renewable and on site generation are innovative approaches to incorporate in the design of new, and retrofit of existing buildings,” says Hoballah. “These approaches not only make the individual building more sustainable, but reduce the infrastructure capacity and costs needed to support the buildings.

“Successful technologies such as solar panels for electricity and water heating, geothermal heating and cooling are already being employed in buildings around the world. The use of these technologies, and others such as wind and hydro-power should be considered where location and conditions allow.

“Any technologies that reduce reliance on expensive and carbon-intensive fossil fuel-based electricity supplies can contribute to creating a greener and more sustainable building sector. On-site generation and capitalising on site-specific conditions, such as geothermal or, in locations with access to water bodies, water-cooled buildings and micro-hydro technologies, or wind, are opportunities that will continue to develop as the sector seeks to reduce the carbon footprint of buildings and reduce the reliance on grid systems.”

More widely, what overarching aims or goals should the global community be aiming towards in terms of carbon? “The global community has multiple goals,” Hoballah continues. “In the area of climate action, the building sector, which contributes a third of all global GHG, must reduce the CO2 emissions from existing buildings and design new buildings with a much smaller climate footprint.

“A broader goal for the building sector is to create buildings that are, in addition to climate friendly, more resource efficient, meaning they must use materials, water, and land more efficiently, generate less waste, and contribute to overall sustainable cities. Buildings must be considered in their context and the demands they place on local resources, infrastructure and land.”


What are the likely timescales before the ISO makes a decision? And if successful, how soon might the metric be rolled out?

“The ISO process involves a series of committee reviews and draft standards that usually takes up to three years to formalise an international standard,” Hoballah concludes. “The CCM however, is currently undergoing a second pilot testing, and the application of the metric for measuring energy consumption and reporting GHG emissions from building operations is available today for voluntary use by building owners, cities or other organisations.”

Perhaps the most telling truth behind the CCM is it represents yet another step towards greening up the global building sector. Given construction remains one of the world’s top industries, and given it took an almighty battering throughout recent times of economic stress, smart movers and shakers are probably already developing the new systems and technologies that will enable the shift to greener construction and living.

Undoubtedly, the drive towards low-carbon buildings offers something of an insight into how sustainable development and a green economy might in the future sit comfortably together. It’s a realisation few businesses will want to miss out on.

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