Part L2 and improved building operation
December 1st 2005 by Alan Aldridge, executive director, Energy Systems Trade Association
The 'bottom line' is that the new revisions to the Building Regulations aim to achieve an overall reduction in carbon emissions of between 24 and 28% for non-domestic buildings over the requirements of the 2002 edition.
Metering - New build or refurbishment of non-domestic properties that are over 1000 m2 in useful floor area (i.e. excluding storage areas, plant rooms and passageways) must include Automatic Meter Reading systems: that is a requirement. This will ensure that operating staff have access to appropriate energy consumption data. With that information, effective energy management becomes possible.
In addition, any renewable energy systems must have dedicated metering. Simply installing renewable generation does not mean it will operate efficiently. Renewable energy systems are assumed to make a nominal 10% reduction in carbon emissions in new buildings, for example. Clearly, that may not happen if they are not working efficiently: hence the Government is insisting that their correct operation can be checked through metering. Of course, if it is intended to export 'spill' (excess generation) to the grid, dedicated metering would have to be installed anyway.
However, energy managers and developers should look closely at the option of including automatic Monitoring & Targeting (aM&T) systems as well. This is not mandatory but the use of this technology does qualify for a further 5% allowance on the CO2 target. In addition, Enhanced Capital Allowances are available for aM&T equipment. The main advantage though is in the long term savings this technology offers.
Installing it when a building is constructed means maximum savings can be made. An increasing number of the major energy users in the UK are using these systems and found them to be highly cost effective. In fact, experience shows that aM&T typically achieves about 20% of the extra carbon savings required by these latest revised regulations - far more than the nominal 5% allowed for. Even though this extra amount cannot be used in planning applications, it does mean that energy and cost savings will be much higher.
Controls - The new regulations impose zone control for the first time. An 'independent zone' is one where usage, occupation times or building services differ from adjacent areas. Each zone must be linked into the heating and cooling services plant in such a way that these only supply services to the zone when there is a demand.
This can often mean plant - especially air conditioning - running at part load. In traditional variable air volume (VAV) systems, energy consumption at part load has been very similar to when the plant was running at maximum capacity due to use of mechanical dampers in controlling flow. There is a requirement in the new regulations for fans to run as efficiently at 25% as at 100% loading. The only practical way of achieving this is to use variable speed drives (VSDs) or inverters. Throttles using dampers do not comply.
For heating systems, further efficiency improvements - and therefore savings - of up to 8% of heating-related CO2 are achievable through the use of Building Energy Management Systems (BEMS) and monitoring controls.
Electricity supply and lighting control - The proportion of the current that does useful work is determined by the power factor - the closer to a value of 1, the more efficient the overall electricity usage.
In the past, utility companies used to charge for inefficient power factor but this has become less common.
So in order to improve the efficiency of electricity usage, the regulations now offer a 2.5% CO2 allowance if the power factor is at least 0.95%.
Most lighting, especially the ballasts for energy-saving fluorescent lamps, have good power factor now.
However, the importance of effectively controlling the lighting systems has also been recognised. By introducing measures such as occupancy sensors, daylight linking and full lighting management systems, the carbon target can be reduced further.
With all these measures, the actual savings will almost always be more than the allowances available under the Building Regulations. So users have a continuing benefit from lower energy consumption. Control and management measures can provide a very cost effective solution, achieving up to half the required CO2 savings - and the environment also benefits. More articles from ESTA: | 
