ASHRAE Journal - February 2015 - S14

Figure 11: Cumulative reduction in energy consumption by applying basic passive strategies.

air conditioning load as demonstrated in Figure 11. This analysis clearly indicated that there is no substitute for a correct
fundamental design and these interventions in early stage of
design can help cut down the annual energy bills of a building
and also optimize the initial cost.

Minimizing Façade Gains through Innovations
As a next step, state-of-art glazing material and technologies that are aimed at providing high performance insulation
(HPI) or solar gain control (SC) or day-lighting (DL) solutions
or a combination were evaluated for analyzing possible further reduction in building energy consumption.
An extremely high performing glass assembly double glazed
unit with aerogel filling (U value of 0.5 W/m²K), when simulated on this optimized building, only provided further 1.5%
savings in the annual electricity bill, thereby reinforcing the
finding that a well-designed façade following the basic fundamentals of design is more cost effective and provides a good
performance compared to using expensive materials like
high-performance glazing solutions.
Green Wall Technology was also simulated to evaluate the
enhancement in the wall performance. Living green walls are
natural air filters, creating a cleaner, more invigorating work
environment that lead to better overall employee health and
production. By incorporating living wall technology, further 3%
energy reduction was achieved on the already treated façade.
The final strategy included Ventilated Double Façades consisting of two panes of glasses and separated by a cavity through
which air flow is encouraged. The driving force for the air flow
is natural or mechanical ventilation which helps in reduction of
the indirect solar gains. The technology helps in achieving further 5% annual energy saving on an already improved building.
Similarly, buildings often have aluminium frame-work to
support the glazing. These frames can add up to a significant
percentage in the overall façade area. Providing thermal
breaks in these non-insulated frames or using non-conducting materials like plastics also yielded up to 5% savings in the
annual operating cost.
Thus, an out-of-box innovative thinking presented a potential of additional 4-5% savings on the energy requirement on
an already optimized façade.
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FEBRUARY 2015

Figure 12: Energy consumption reduction using innovative technologies.

Façades of the Future... the Trendsetters
Some of the technologies on the horizon are:

Façades Generating Power-Photovoltaic Glass Unit (PGU)
Building integrated photovoltaic (BIPV) captures solar
radiations and turns them into usable energy. With current
efficiencies up to 12%, they have a long way to go before being
commercially viable. The advantage of this technology is that
it does not compromise the fenestration quality as PGUs provides transparency up to 70% to the human eye.
Energy Generation Potential: For the Indian climate, electricity produced by Photovoltaic Glass Unit system (PGU) in just
1 sqm of area can vary between 40-60 kWh per annum - sufficient energy to supply up to 20,000 hours of light from 20W
energy saving light bulbs.

Thermally Dynamic Façades-Phase Change Materials (PCM)
Thermally, dynamic façades uses phase change material
wherein a layer of salt crystals captures the heat radiated
by the sun and releases it back to the environment during
non-operational hours. They basically function as a thermal
mass and accomplish that by liquefying as they absorb heat,
preventing the heat from reaching the conditioned space and
releasing the heat when the outside temperature decreases,
typically at night.

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.
The 10 storey building was designed by DesignInc in conjunction with the City of Melbourne and obtained the six green star,
in part, because of its many innovative and technological features including photovoltaic cells. The most striking features of
CH2 are its recycled timber louvers controlled by photovoltaic
cells and the five shower towers, 1.4 meters in diameter and
13 meters long, that draw air from over 17 meters above street
level, in which water droplets evaporate slightly as they use up
energy and, thus, cool the air. Shower towers lower air temperature to around 21°C (from around 35°C) and water temperature to 20°C.

ASHRAE Journal - February 2015

Table of Contents for the Digital Edition of ASHRAE Journal - February 2015