8. Complex Systems

The design and installation of low carbon heating and ventilation is complex. The efficiency of the heating system will depend on assumptions about:

• the existing home;

• occupancy and hot water usage;

• careful house-specific design;

• specification of the whole system, including radiators and water storage;

• installation of the system and correct commissioning and setting up.

There may also be simple explanations for underperformance arising from user misunderstandings or lifestyles. Other problems may not be to do with lifestyle. There are many variables and many interacting elements. Unfortunately, unless there is in-use monitoring by experienced engineers, any underperformance of controls and systems may be difficult to diagnose.

Smart metering and feedback may help but without more sophisticated information (for instance, separating the energy consumption for hot water and heating) and without some environmental context (the typical external and internal conditions and behaviour) diagnosis can be difficult. As we switch to low carbon heat we can expect challenges from rapid changes, increasing complexity and unfamiliarity with the technology.

An unexpected consequence of this transformation is that when things do go wrong, we may not know why.

There are some steps in the revised Approved Document Part L to help ensure that accurate information about the construction and equipment installed in the home is passed on to the homeowner. Whilst this may give some comfort of construction quality it is a long way from assuring or guaranteeing a home’s performance.

Things that can go wrong:

• Inefficiencies difficult to identify;
• Underperformance of systems (rather than individual components);
• Diagnostic skills not available to correct inefficiencies.

Future-proofing recommendations:

• DESIGN: Industry recommendations for implementation of research/knowledge centres;
• INSTALL: Skills and training for management and maintenance as well as design/installation;
• COMMISSION: Accurate commissioning and set up will be essential together with monitoring and diagnostic tools built into equipment.