Facades Buildings Energy Efficiency
Façades For High Performance Buildings | Facades Buildings Energy Efficiency

Exponential growth in population over the last century and rapid urbanisation in developing economies has made a significant impact on climate change. Consequently, nations across the world has identified ‘energy efficiency’ in built environment as a low hanging fruit that can help in protecting the environment _ and the focus is now on lowering energy demand of existing buildings and regulating the consumption of new stock. Indian construction industry is at a critical juncture wherein it has to balance the demand of low cost construction – but simultaneously comply with the stringent environmental and efficiency norms that are becoming order of the day. With majority of building in India expected to be constructed in next three decades, the experts are working towards creating a balance between the technology from western world and old wisdom of Indian buildings that evolved over a period of time in harmony with nature.

Building façades

The architectural facade has long been a compelling focus of interest for building physists and designers combining attributes of both appearance and performance in a holistic manner. Facades form a building envelope form the outer skins of buildings as a project image and creative intent. Increasingly, they are also understood as important environmental moderators. A thoughtfully designed skin can make a new building work more effectively for its owners, occupants and environment. It can also transform the performance of an existing building. The technology has gradually emerged in the recent decade, driven largely by the pursuit of transparency in the building facade among international building designers. The facade is also the focal point of energy efficiency in a building design _ because it works as the first frontier to face the intense heat and a major source of heat ingress into the buildings. As an enclosing building component, it connects or separates the interior and the exterior.

All components of the building facade, therefore, need to work together to regulate the indoor environment, responding to heating, cooling, ventilation, and natural lighting needs. It must balance requirements for ventilation and daylight – while providing thermal protection appropriate to the local climatic conditions. The optimally designed building facade is an important factor – not only for achieving the energy efficiency, but also the human comfort for which the buildings are actually designed.

Further, a building facade can have both positive and negative effects on work performance. Negative effects are associated with discomforts, distractions or health risks that interfere with peoples’ ability to do their work – whereas positive impacts are associated with enhancing work performance, psychosocial well-being and health to enhance the overall performance.

Façade implications on occupant health and performance

Performance enhancement is more likely to come from a different set of building features and attributes, which affect performance. Lighting, which produces glare or visual discomfort, is more likely to be associated with headaches and eye problems. Glare due to direct solar penetration and due to the lack of luminous uniformity across the space distorts the perception of good indoor daylighting.

As per a field study of office workers, it is found that workers who had window views of nature felt less frustrated and more patient, and reported more overall life satisfaction _ and better health than workers who did not have visual access to the outdoors or whose view consisted of built elements only. The positive effects of nature may also extend to the immune system, thereby directly affecting human physical health.

Thus, one of the perennial challenges in designing facades is to achieve an even distribution of diffused daylight across the building section.

Various computer simulation models like daylight distribution studies; visual comfort and glare analysis help optimise the building design to enhance performance and achieve visual comfort at the same time. These simulations evaluate building designs to identify potential concerns related to daylight distribution and provide solutions to ensure appropriate illumination of spaces.

Some images have been given below to demonstrate the pattern of direct sun ingress into space and subsequent placement of workstation to achieve glare free daylight in indoor spaces:

By conducting these simulations at AECOM for our clients, we have experienced that these simulations assist Architects, Engineers and Designers to design spaces with balanced luminance on different interior surfaces _ and achieve overall efficiency and visual comfort for the occupants.

Facades of the future… the trendsetter

Catering to the demands of an ever expanding industry and innovative designers, the presentation shifts in its last segment to sensitising on the future technologies in building facades, which will provide better efficiency, aesthetics and commercial value to the developments _ addressing a wider spectrum of issues covering following:

• Facades generating power – Photo voltaic Glass Unit (PGU): Building integrated photovoltaic’s capture the solar radiations and turn it into energy. A high level of energy generation (up to 12% efficiency) can be generated through Photovoltaic Glass unit. The advantage of this technology is that it is allowing the usage of fenestration part of the building as PGUs provide transparency to human eye up to 70%. •

The energy generation potential: The electricity produced by Photovoltaic Glass Unit (PGU) system in just 1 sqm of area can vary between 40 to 60 kWh per annum; sufficient energy to supply up to 2000 hours of light from 20 W energy saving light bulbs.

• Thermally dynamic façades – Phase Change Materials (PCM): Facade, which responds in accordance with the variations in outdoor conditions. Thermally dynamic facades use phase change material _ wherein a layer of salt crystals capture the heat radiated by the sun _ and release it back to the environment during nonoperational hours. The thickness of conventional materials used in buildings is much more than the equivalent heat capacity of a onecentimetre- thick PCM.

• Bio mimicry in façades – living buildings: Just like the surface of a leaf, the ‘skin’ of future buildings may react to external stimuli, opening, closing and breathing throughout the day through a system of ‘cellular’ openings that allow light, air and water into the apartments contained within.

• Facades enhancing outdoor environment – microclimate impact: Growing vegetation on the facade can potentially create a positive microclimate around the built form. A microclimate is a local atmospheric zone _ where the climate differs from the surrounding areas. The studies account that a reduction of approx. 2˚C can be achieved by using green vegetation around buildings compared to the surrounding ambient in composite climates like Delhi.

• Facades enhancing indoor environment – growing fresh air: Most developing countries have high pollution levels _ and as a result the indoor environment can be even more polluted. Drawing ventilation air through a green facade or a greenhouse offers a potential to counter the toxins, VOCs, microbial infections etc., in an airconditioned building.

• Façade addressing fuel crises – building powered by algae: A classic example for this technology is BIQ building algae panels generating power where the algae is grown on facade and burned to provide an alternate energy source.

• Facades addressing food crises – Hydroponics: The idea that fruits and vegetables can grow with water, light and nutrients is the basis of hydroponic: one of the innovative systems of making the building self-sustaining. There have been other numerous advantages of this system as well. A reduction is seen in street level concentrations up to 40% for NO2 and 60% for particulate matters. They potentially contribute to an increase in biodiversity in urban areas by providing a habitat for birds etc. The most important aspect is their ‘rejuvenating effect’ on the living creatures around as they contribute in softening of the urban landscape and allowing buildings to seem more ‘natural’ and pleasing for the people.

Conclusion

Energy efficiency is a primary challenge in today’s commercial construction industry. How important are energy efficiency gains from a building envelope is a topic that is gaining momentum amongst industry-leading architects and design firms. In order to address a few paramount issues in the industry, with ever-increasing pressure for the dual objectives of higher performance and improved payback calculation to stakeholders, innovative trends and forces are shaping the future of building skin. They contain the answers to many unfolded domains.