Measure for measure

After wide ranging consultation that must have left them cross-eyed, the crafters of Part L: 2005 are expected shortly to issue the long awaited draft. The delay would be well justified if it admits our world leading dynamic software products as alternatives to the simpler National Calculation Tool for calculating the asset rating of buildings. One of the features of the Energy Performance in Buildings Directive (EPBD) is energy labelling of non-domestic buildings through measurement. I gather that the EPBD's stipulation that labels are displayed in 'public buildings' is to be given the meanest interpretation of only applying to government buildings. But the EPBD also requires the same energy data-set, the operational rating, to be available to prospective purchasers and tenants – displayed or not!

This is a fascinating proposition. Developers and owners will have to get an asset rating as part of Building Regulations compliance, but they'll then be faced with hard operational rating data two or three years after occupation. How will they compare? In my experience fitting energy computation to measured results is troublesome. But attempting this reconciliation is often fecund – exposing that sometimes massive gap between the designer's intent and the operator's ignorance of it.

It's not clear how energy labelling will be enacted in UK and whether Part L is the right instrument – even though its requirement for metering has little value unless the results are used. I guess we'll find out soon.

The key issue is whether meeting operational rating targets could ever form part of the pass/fail regulatory mechanism. 'Proving' already features in various regulations but how could energy compliance be enforced say three years out? Closing down the building is hardly a starter. Carbon trading might provide a penalty system – surcharging the energy user with the market cost of its excessive carbon emissions. However, this would be brave at the moment.

   The beauty of using the operational rating as the regulatory metric is that it's real. It is also the only measure that engages owner, operator, designer and builder in the imperative of delivering real carbon emission performance. There are operational rating methodologies that reconcile design prediction and normalise operational outcomes – and even attempt to apportion the responsibility for discrepancies.

If we want to differentiate our expertise, we must take responsibility for things that no one else can do.

The problem is how would a Part L compliant asset rating sit aside a non-compliant, but normalised, operational rating? The usual outcome in such cases is massacre of the innocents. Yet any measure that draws designers and installers back to proving the delivery of intent must be right. There's an evolving realisation that keeping the delivery team engaged for a while after hand-over is one of the best investments a client can make.

And if it comes to massacres, perhaps we're not all innocents. Word on the street is that some of us are playing the 'Part L – I can fix that for you' card. If we want to differentiate our expertise it won't come through railing in the letter pages of BSj against the 'engineers' who deliver and tune in our new tellies – but by doing, and taking responsibility for, things that no one else can do.