Letters

Our industry’s Part L calculations are let down by poor data

In his article, ‘Fabric of success’, in the April issue of the Journal (page 22), Hywel Davies states that buildings are using more energy than suggested by Part L calculations and, suggests this is because the buildings are not built as they are specified. One reason for this may be that the software used to produce the Part L carbon emissions calculations is flawed. For example, in the NCM (national

calculation methodology) database, a bedroom in a residential nursing home is shown as being unoccupied for 10 hours a day. But in my experience of such homes, the residents remain in their rooms, generally with lights and televisions on, for most of the day. Libraries, museums and galleries are included in the database as being closed at weekends and holidays, but surely these are their busiest times, when air conditioning, heating and lighting systems are working the hardest? The same can be said of most of the

data sets used by the SBEM software, and surely any other software package that uses iSBEM for its calculation engine will produce inaccurate results and low carbon emission figures. Until the information used by the software to calculate the carbon emissions better reflects the way buildings are used, the energy consumed will always be higher than predicted, even if a building is constructed exactly as designed and specified and operated to its most energy efficient.

Phil Dodd

Collaboration? Let’s just do it!

Having attended the CIBSE annual general meeting last month and applauded Rob Manning’s presidential address (see May Journal, page 34), I am convinced the collaboration theme needs to be adopted widely, and extended across many of the boundaries which currently fragment our industry, if we are to deliver low carbon buildings. However, it may mean a radical overhaul, or even replacement, of our current competitive tendering process, as clients who can ill-afford it are keeping down their operating costs at the expense of those in the supply chain – consultants, contractors and manufacturers. I cannot help thinking clients would be much

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CIBSE Journal June 2010

and contracting colleagues. We at Lindab are frustrated by the lack of attention paid to ductwork in terms of its potential contribution to energy conservation. While inefficiencies in other types of building services equipment are analysed in minute detail, high leakage rates from ducting go largely ignored. Sophisticated and expensive solutions, such

as fans and controls, are selected to reduce the energy consumed in generating air supply, but little or no attention is paid to the efficiency of the system that will transfer that air to where it’s needed. At current ductwork leakage rates, much of the energy saved by the fan will simply be blown out of the building. There is a solution. Moving up from the current ubiquitous class A ductwork system to

more discerning if they had to face the real cost of securing a price for planned work. But, as Rob Manning says: ‘don’t wait – find a way and just do it.’

Andrew Saville, CEng, FCIBSE, MSLL

We need a better class of ductwork

Mention of the huge waste of energy created by air leakage from ductwork in your air movement feature (May, page 55) has sparked a good deal of interest among our consultant

a class C one represents a nine-fold reduction in permitted losses. What other affordable and easily achievable measures could offer this magnitude of improvement in energy efficiency?

Iain Robertson

Joint managing director, Lindab Ventilation

Burning pellets? It’s back to the 1900s

In the 1960s I designed many domestic central heating systems in Hampshire, UK, to bring alive the vision of the 1970s housewife standing proudly alongside a clean, quiet and automatic piped fuel boiler in a modern kitchen. We removed cast iron coal burners from kitchens and coal cellar boiler rooms from houses to crypts, to the great relief of many a person and parson. Today we blanket our entire planet

with artificial daylight all night, and air- condition excessively glazed buildings in a UK climate that barely needs it. We burn solid fuels in hand-stoked boilers. How long will that fad last? About as long as it takes the home, school and fire station operators to find carrying bags of fuel and emptying ash cans tiresome and dirty. If we are to turn the energy clock

back to the early 1900s, why not bring back coal stoves, have no central heating, have operable windows and natural ventilation, low-rise buildings, small windows, draught excluders, no air conditioning, vastly reduced lighting, bicycles, trams, cheap train travel and walk a lot. Not convinced? Well, we are not

serious then, and just love to talk about it and write massive documents – oh, maybe that is the point.

David Chadderton, Australia

dchadder@ncable.net.au

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