woman working on computer in office

You’d think that people in a green rated building would be keen to maximise the energy performance of their building p- switch off lights and so on.  Not so, these researchers found, among other curious patterns.

Our 2020 study concluded that occupants are the most impactful factor affecting energy consumption in buildings. Other researchers have asserted that improving occupant choices are imperative to increase sustainability within our built environment. 

The use of new technologies, methodologies and sustainable certification tools is insufficient if the people who interact with these systems are unaware of their optimal utilisation. 

From our current research, the difference of energy consumption between an unaware energy user and an aware one is 72 per cent.

Understanding the complexity of occupant behaviour and what drives occupants’ choices has seen an increasing research interest in the past 10 years. According to the International Energy Agency (IEA), occupants’ energy actions are influenced by several contextual factors, called driving forces, which may be intrinsic to the individual, such as socio-psychological and biological aspects, or external to the individual as physical environmental elements.

Figure 1. Driving forces that impact occupant behaviour when interacting with energy Source: International Energy Agency 

Most energy and sustainability rating systems ignore the variability of occupant behaviours. This variability is one of the main contributors to the gap between the energy predicted during the design and the actual produced in the operations stage in buildings. 

In a study conducted on two university buildings with similar characteristics in terms of floor area, usage, activities, type of systems, one green rated and another one without any rating, 81 per cent of the occupants were unaware on how to efficiently use the building systems and features. Occupants were not trained on optimal behaviours when using the buildings. 

However, the energy consumption of the green building was only 25 per cent lower than the non-rated one. Moreover, both buildings had similar annual energy intensities (187 and 190 kWh per square metre respectively). 

This last fact was a surprise taking into consideration that the green building during its design and conceptual process followed best practices. Its systems were more efficient than the ones in the non-rated building and several energy efficient strategies were implemented. Therefore, the annual energy intensity in the green building should have been lower than the non-rated one. In other words, the energy savings should have been higher.

As an example, the lighting system in the green building is 31 per cent more efficient than in the non-rated building, and the equipment uses 44 per cent less energy. 

When analysing the occupants’ behaviours, there was no significant improvement in the use of energy between the occupants from the green building and the non-rated one. In fact, the occupants from the non-rated building were more proactive when interacting with energy systems, than the occupants from the green building. 

For example, 66 and 46 per cent of the occupants in the non-rated building switched off their computers and lights at the end of the day, contrasting with 32 and 34 per cent in the green building, respectively. 

Additionally, older generations were more proactive than younger ones, and women more than men. The location and the size of the workplace also had direct impact in how occupants use the lighting system. 

Occupants in open spaces tended to have less energy conservative behaviours than occupants in a private office. Therefore, it is possible to conclude that the positive difference addressed previously is not so much related to an aware type of occupant but more to the use of improved technologies. The study also showed that the green rating by itself is not relevant in energy conservative behaviours. 

The green building was operating as if it were a non-rated one. The difference between the energy intensities of the two buildings is only 2 per cent. 

If the green building was operating within the same criteria by which was certified as “green” and its occupants were more aware of their impact in the overall building energy performance, this difference would have been more significant. 

This corroborates the assumption that the implementation of new strategies and/or technologies is not enough if the human factor is ignored, as it is possible to see from the overall energy intensity in the two buildings. 

Maintenance is an issue

The role of a proper maintenance is also relevant to ensure an appropriate and efficient use of resources. 

Providing information to people and explaining the purpose and how the building and its systems work is crucial if we really want to move towards a more sustainable world. 

One of the insights from our research is that all buildings should have accessible information articulated in a users’ building optimal performance (U-BOP) manual that teaches occupants how to use their systems and resources (lighting, airconditioning, equipment, water, materials) efficiently. 

We urge buildings’ owners to make the optimal performance manual available to all occupants, and the maintenance teams to ensure that all occupants interact with the buildings’ systems and features efficiently. Promoting awareness is critical. As mentioned previously, our study showed that only 19 per cent of the occupants had some knowledge on how to efficiently use the building systems and features. 

It is imperative to forge a coherence between the true meaning of sustainability and our daily actions. Without the cooperation of all the different actors involved in buildings, sustainability is just another fancy word. 

Dr Laura MMCE Almeida, Professor Vivian WY Tam and Associate Professor Khoa N Le teach and research at Western Sydney University. 

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