Heating

Offices are rather different. Solar gain needs to be cut out rather than enhanced. However, orientating a building along an east/west axis so that the main facades face north and south can achieve this simply and cheaply - as long as the southerly façade has shading provisions.

High levels of insulation address fabric heat losses. Under current building regulations wall U-values are typically around 0.25 W/m²K*, though passive houses can have values as low as 0.1 W/m²K. Windows currently achieve typical U-values of 1.7 W/m²K, though in several EU countries the standard is now as low as 1.3 W/m²K, with values as low as 0.8 W/m² becoming increasingly common in more ambitious projects.

By creating an air-tight shell, uncontrolled ventilation losses can be minimised. Once this has been achieved, passive house design standards can almost dispense with space heating requirements, providing that sufficient solar gain is designed in. The German ‘Passivhaus' standard uses forced ventilation with heat recovery, ensuring that ventilation air changes do not result in unnecessary heat loss.

A housing development in Stawell in the south west of England provides a good case study in achieving air tightness.  Click here to view.

The level of policing of building standards is a key consideration. The UK focuses, perhaps unduly, on the theory, and yet our buildings notoriously perform below par once built. Perhaps one of the most important elements of low carbon design yet to be addressed in the UK, is the quality of the final build, and the level to which the theoretical designs have been implemented.

Commercial buildings are have typically much greater levels of central control, but often fail to make the leap from theoretically efficient design to actual performance. Here facilities managers and other occupants of the building need controls which can be operated simply and intuitively. Current building regulations require new non-domestic buildings to be handed over with a log-book that explains key servicing principles.

Key principles are to match services hours closely to occupancy hours and to optimise set points, ie to heat to the minimum acceptable level and only cool to the highest acceptable temperature.

For more detailed information refer to the following EST guide here.

This shows that occupant education is key: occupants need to understand the energy efficiency concept of a building and how to use controls. Commercial building occupants who may not have control over heating need to understand the heating policy of the organisation, which may contain set points which may not match their expectation of comfort exactly, but which they can adapt to with simple measures, such as appropriate clothing.