Last edited 17 Jun 2021

Zero carbon non-domestic buildings


[edit] Introduction

The Climate Change Act was introduced in the UK in 2008, creating a long-term, legally-binding framework for tackling climate change. It set a target of reducing carbon emissions by 80% compared to 1990 levels by 2050, with a reduction of at least 34% by 2020.

A strategy for how this was to be achieved was set out in The Carbon Plan published in December 2011. Buildings form a significant part of the plan as they account for around 45% of our total carbon emissions.

In December 2006, the Labour government committed that from 2016 all new homes would be ‘zero carbon’. The Labour budget in 2008 announced the government's intention that all new non-domestic buildings should also be zero carbon from 2019. This commitment was confirmed by the Coalition government in December 2010.

This meant that the timeframe for zero carbon non-domestic buildings was three years behind that for zero carbon homes. Consequently, progress towards defining a zero carbon standard for non-domestic buildings was similarly behind.

It was considered that the overall approach to achieving zero carbon non-domestic buildings would adopt a similar 'fabric first' hierarchy of measures to those proposed for domestic buildings:

  1. Fabric efficiency to reduce the demand for heating, cooling, mechanical ventilation and electric lighting.
  2. Meeting the remaining demand for services with high-efficiency equipment.
  3. Supplying that equipment with low carbon energy.
  4. Offsetting remaining emissions by generating further renewable energy off site (such offsetting measures are called ‘allowable solutions’).

There were however a number of highly complex questions to be answered relating to the application of these measures:

For example, technically, it may be possible to comply with a zero carbon requirement by adopting low carbon technologies rather than by a creating an energy efficient fabric, and from the developers perspective this might be cheaper in the short term. However this might not minimise whole-life costs (due to the ongoing costs of fuel, maintenance and replacement). In addition, technological solutions are prone to operate below their optimal level of efficiency because of the behaviour of occupants, poor commissioning and maintenance. Furthermore, optimising the building fabric would be likely to give a building better resilience to climate change and continuity of energy supply.

On the other hand, build quality has a big impact on the effectiveness of energy efficient fabric, and is much more difficult to correct than user behaviour. Also, technology replacement offers the potential for future improvement in efficiencies that are difficult to achieve with building fabric.

These are more difficult questions to answer than for domestic buildings, as there are such a diverse range of possible building sizes, forms, types and locations to consider.

In addition, unlike domestic buildings, electric lighting is a very significant component of energy use and this results in a more complex trade off between natural lighting and fabric thermal efficiency. Continually increasingly standards for U-values has a diminishing return relative to cost whilst there is considerable scope for efficiency in services equipment.

There were also a number of options for how a zero carbon standard might be enforced, however it was expected to be based on assessing carbon compliance using existing techniques which compare the relative performance of the proposed building with a notional building of the same size, shape and use. In addition, minimum efficiencies were expected to be set for key measures such as U-values and solar gain as well as the main services equipment and electric lighting.

As with zero carbon homes, unregulated energy (such as appliances) was expected to be excluded from emissions calculations.

The standards to be achieved were to be set out in the building regulations and associated approved documents, in particular Part L, the conservation of fuel and power. The overall standards set in the current 2010 Part L are based on achieving a percentage reduction in carbon emissions compared to the carbon emissions of a building of the same type, size and shape built to 2006 standards. Revisions of Part L in 2013 and 2016 will require larger reductions in these carbon emissions compared to the 2006 standards, and were to progress towards the ultimate goal of 'zero carbon' by 2019.

[edit] Fixing the foundations

However, on 10 July 2015, the government published ‘Fixing the foundations: creating a more prosperous nation’ a government plan for increasing Britain’s productivity.

Amongst a great number of wide-ranging changes, the report states, 'The government does not intend to proceed with the zero carbon Allowable Solutions carbon offsetting scheme, or the proposed 2016 increase in on-site energy efficiency standards, but will keep energy efficiency standards under review, recognising that existing measures to increase energy efficiency of new buildings should be allowed time to become established.'

The announcement did not specifically mention proposals for zero carbon non-domestic buildings, but it has been widely interpreted by the industry as signalling that these have also been scrapped.

It is not clear where this leaves the UK in fulfilling its requirements under the Energy Performance of Buildings Directive to move towards nearly zero energy buildings.

[edit] Ongoing debate

In November 2016, the House of Commons Environmental Audit Committee report on Sustainability and HM Treasury critcised the government for scrapping the zero carbon buildings standard and called for it to be reinstated.

[edit] Related articles on Designing Buildings Wiki

[edit] External references.

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