energy demand

The initial design concept for the Lighthouse Building refurbishment consisted of an insulated steel clad facade, insulated lead sheet roof, extensive use of double glazing and slate covered concrete floor with external insulation. The building services comprised embedded floor heating, halogen display lighting and natural ventilation from vented slot windows.

A number of reference models were developed to assess the contributions from alterations to glazing systems, the adoption of critical control strategies and the incorporation of various passive and active renewable energy technologies. The first reference model replaced the standard double glazing with low e coated, argon filled triple glazing. This resulted in a 58% reduction in annual heating energy and a 31% reduction overall energy requirements (heating plus lighting). Further reductions were achieved using daylight responsive lighting control. The addition of a south facing transparent insulated (TI) thermal mass wall reduced the duration of the heating season supplying the building's heating requirements during transitional seasons, while auxiliary heating was confined to the winter period.

The cumulative effect of the advanced glazings, lighting control and TI facade resulted in a 45% reduction in annual heating energy, 59% in lighting energy and a 51% reduction to the overall annual energy demands. The next evaluation case replaced the underfloor heating system with a fast response, critically controlled, convective heating system and halogen lamps with high efficacy luminaires. In comparison with the original design hypothesis, this resulted in a 58% reduction in annual heating energy demand, a 67% reduction heating plant capacity, an 80% reduction in lighting energy demand.

Implementing the above measures not only achieved a high level of demand-side energy reduction without compromising the building's thermal and visual comfort levels, but increased the effectiveness of the deployed active renewable energy systems in meeting the remaining energy demands.