4: The Benefits

This energy consumption accounts for a significant proportion of a building’s energy use. Passive solar design can therefore lead to significant energy cost savings over the life of the building. Passive systems are often simpler and, if commissioned properly, cheaper to maintain. If there is any increase in capital cost, it is likely to be repaid five to six times over a 20-year period by operating cost savings, depending on the building type (Ministry for the Environment, 2005).

Because passive buildings also tend to be more integrated, the building system required can be less sophisticated. As a result, passive solar buildings are often more flexible and durable which ensures a longer life (Cole, 2000).

Buildings with a high degree of natural light and ventilation also tend to be healthier, more pleasant buildings to work in, so users are easier to retain and are less likely to take sick days, meaning a ‘hard’ productivity benefit. Hard productivity benefits include reduced absenteeism, staff turnover and churn, which are easily quantifiable.

Soft productivity benefits relate to users being more productive because they are happier with their environment. This is much more qualitative, though studies have suggested a link between daylight and natural ventilation in schools and improved student performance (Heschong Mahone, 1999). A more healthy environment is particularly beneficial in hospitals, where the use of natural ventilation instead of recirculated air reduces the spread of airborne infections (Arup, 2008). It has also been suggested that higher levels of natural light improve patient recovery times.