Policy analysis Part L
The CIBSE energy hierarchy explained
Fabric energy efficiency – make the building envelope as efficient as reasonably possible for all buildings, using all available passive means. Incorporate back- stop requirements for solar gain and airtightness as well as an overall KWh/sq m/annum target.
Energy efficient plant – install energy efficient heating, cooling, ventilation and (if needed) refrigeration plant, lighting, and other energy using systems such as lifts, escalators and other, long life energy using equipment. NOTE: this requires some currently unregulated uses of energy to be brought within the scope of Part L in the future (2013 or 2016). Energy efficiency systems – reduce energy demand of installed plant at the systems level, with: controls
Source: CIBSE
Zero Carbon
Allowable Solutions
Renewables
Energy Efficient Systems Energy Efficient Plant
Fabric Energy Efficiency Carbon Compliance
that are installed and commissioned; trained operators; and maintenance and management systems. It is far too easy to install state-of-the-art, energy efficient kit, but then to connect it together in inappropriate ways, with inadequate controls and operator or occupant training, and lack of awareness and insufficient maintenance. The dream specification delivers nightmare performance, with emissions to match and energy costs to make the nightmare recur every time a bill comes in. Only once we have energy efficient fabric and
efficiently operating systems should we move to provide renewable energy to power those systems, whether on site, off site, or a mixture of the two.
We need to
ensure that buildings are built, signed off and operated as they were designed to
Min. Level
minimum values should apply to air tightness, solar gain and heat loss, as they do in Part L. However, the kWh/sq m/year metric will be a real
problem where different fuels with different emissions factors are used. You cannot add x kWh of electricity to y kWh of gas. If you want to know the carbon emissions you must first convert each kWh figure to carbon, using the correct emissions factor, and then
add the emissions, not the energy figures. According to the CLG consultation, other options for allowable solutions – apart from off-site renewables – include advanced building controls, energy efficient appliances and renewable heat provision. But CIBSE’s view is that controls are a current
requirement of Part L, and so should not be classed as an allowable solution. Indeed, controls systems should
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www.cibsejournal.com
April 2010 CIBSE Journal
23
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