Passive Solar Architecture – Returning to first principles (Published in Times Property [Bangalore], Times of India, 25 May 2013)

Introduction

The aim of this article is to introduce the reader to the concept of passive solar architecture and to stress its importance for achieving building energy efficiency. 

“The passive solar concept is to allow nature to operate our systems with a minimum of mechanical interference. We know that the potential for heating, cooling, and powering our dwellings, factories, and office buildings by non-mechanical means exists. Our ability to allow this to happen is limited only by our imagination.” 

David Wright, AIA

In today’s context of global warming, the quote, by one of the foremost proponents of Passive Solar Architecture, is an important reminder for a more sustainable way of designing, building and operating our buildings. 

The concept of passive solar architecture has existed since time immemorial. Human beings in the pre-fossil fuel era have always built their dwellings with intelligence combined with an intuitive understanding of their environment. The introduction of fossil fuel fired machines with unprecedented efficiencies and increasing monetary prosperity has led us to the point of climate change. It is widely accepted that buildings contribute to about 40% of the global greenhouse gas emissions. 

McKinsey and Co in its report titled “Environmental and Energy Sustainability: An approach for India” states that approximately 42% of GHG abatement potential can come from designing an efficient building envelope design itself. The idea of building in sync with nature is no longer a romantic notion by a few architects but an important approach that needs to be taken seriously by the building industry at large. It is a discipline that demands a thorough understanding of the context coupled with a common-sense approach to design. 

A return to Passive Solar Architecture

Buildings are subject to various forces of nature. Most of the elements get included in the broad terminology of climate. Aspects covered under climatology include temperature, rainfall patterns, wind speed and direction, and relative humidity.  Other contextual factors include topography, nature of landscape, longitude and latitude of the building site among others. 

The period starting in the 1950s saw the development and application of building physics, as we understand it now and for about three decades played an important role in the design of buildings. With increasing affluence and breaking down of import barriers, developing countries like India saw a proliferation of material choices that were hitherto unavailable to the average Indian designer’s palette. It was at this point that the average practitioner of architecture made a radical departure from passive solar design to designing buildings with little sensitivity to ecology. It also saw a leap in reliance on active systems like air-conditioning and artificial lighting.

Studies carried out by a team of which the author was a part of, have shown that a building could save as much as 10% (in annual energy consumption) by altering the shape of a building (for the same given area). Another study done by the same team has shown that altering the orientation of a building could save as much as 5% in annual energy consumption. These studies therefore underscore the importance for architects to return to their understanding of climate, ecology and building physics. 

The need for inter-disciplinary collaboration

The 9% GDP that India has been witnessing in the last decade has resulted in more complex building types (from the point of view of building use) with complex and multi-disciplinary design inputs. This has necessitated higher and deeper involvement of specialist professionals. However, in most cases the designs are created and conceptualised by the architects without the inputs from the specialist professionals. This results in non-optimised active systems to achieve acceptable performance parameters. A typical case in point is the indiscriminate use of glass without consideration of the orientation of the building. Large area of glazing on the western façade of a building results in higher sizing of air-conditioning chillers and consequently higher sizing of electrical services. Scenarios such as these can be avoided by adopting an integrated approach to design where in architects and other engineering disciplines work in tandem to develop the concept design. 

There is also a certain level of shortsightedness that exists on the part of the building industry while examining the aspect of “Total Cost of Ownership”. TCO is a common enough concept in the automobile industry. Every prospective car owner considers the TCO while buying a car. However, building owners rarely consider this and hence end up investing in areas that are low on capital expenditure while ending up paying higher in operational expenditure. 

Using software tools – Building Energy Simulation Software

The use of computers as a means of drafting and modelling has become a norm in the Architectural and Engineering Consultants (AEC) industry. Building energy modelling is an important tool that aids in predicting the energy demand of the building even before it is built. There are many tools available in the market – Ecotect, IES-VE, eQuest, Visual DOE, Radiance among others. 

In the pre-software days, an exercise in building energy modelling would take days if not weeks. The introduction of software with pre-loaded climate files and profiles and properties of building materials has drastically cut down the time required for building energy modelling. Many software applications can guide and inform the designers on the impacts of their decisions right from the concept development stages through to the final detailed design stages. It also has modularity in terms of linking up with other building modelling software programmes like AutoCAD, Revit and SketchUp. 

Software vendors also offer specialised training programmes to the individuals or organisations that purchase their products. This helps in reducing the entry barriers for consultants to adopt energy efficient design practices. 

The need to re-focus in education

One of the primary areas to focus is on tertiary education in the fields of architecture and engineering. Until now, sustainable design of buildings is subject of postgraduate specialisation. We can no longer afford to relegate training and education in building energy performance to a single subject in a 4 or 5 year or to a postgraduate course. This needs to become an integral part of training in design thinking. Passive solar architecture needs to be taught with a lot of rigour and discipline until it becomes as important as the functionality of the building design.

Mandating minimum building performance

Many countries across the world have mandated building energy performance. India has also created the Energy Conservation Building Code 2007 (ECBC) (based on the Energy Conservation Act 2001) that stipulates the performance of following aspects:

- Building Envelope performance

- HVAC

- mService Hot Water and Pumping 

- Lighting

- Electrical Power

However, ECBC has not yet been implemented in most states. The implementation of ECBC will pave the way towards creating larger awareness on the need, benefit and methodology of achieving building energy efficiency. 

Conclusion

It has become imperative for the AEC community to re-focus on the passive solar architecture and ensure that the first level of building energy savings is extracted through this route. Efficient technologies can then be optimised in order to bring about a well-engineered environment. 

It is time that we take cue from these words spoken by the wise American architect, late Malcolm Wells.

"...We live in an era of glitzy buildings and trophy houses: big, ugly, show-off monsters that stand—or I should say stomp—on land stripped bare by the construction work and replanted with toxic green lawns. If the buildings could talk they would be speechless with embarrassment, but most of us see nothing wrong with them, and would, given the opportunity, build others like them, for few of us realize that there's a gentler way to build.”

(Published in Times Property (Bangalore), Times of India, 25 May 2013)