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Unless ‘sufficiency’ is addressed with same rigour as ‘efficiency’, energy usage is inadvertently increased resulting in a rebound effect.



Rapid urbanization in India in the past two decades increasingly lead to the designing of buildings that endure only by using air conditioning and artificial lighting. Total construction of floor area is expected to increase by about 80% from 2010 to 2030 out of which 32% (15,636 million m2) is estimated to be “cooled floor area” (1). Energy consumption due to space cooling and lighting from the building sector in 2010 was 45% (2) of the total electricity generation of 816.5 TWh (3) in the country. By assuming very conservative ball park figures that all new buildings will be built to prevailing efficiency standards such as BEE or GRIHA rating, air conditioning and lighting is likely to consume up to 650 TWh by 2030. To meet this demand considerable increase in the production of electricity is needed which leads to increased carbon emissions.

More than 80% of India falls under hot-dry, hot-humid and composite climate and has developed a legacy of vernacular buildings to provide comfort and to cater to social needs. Despite considerable research in vernacular and modern passive building techniques, several technical, social and economic aspects along with the lack of authoritative studies on their validity in modern context drastically limits their application (4).

Building energy codes, seldom address ‘passive’ techniques with the same technical rigour compared to ‘active’ measures. Building codes should include means to benchmarking a building’s ‘passive design potential’ instead of adopting a ‘U-Value and equipment efficiency’ approach. E.g., code permits the use of glazing up to 60% whereas only 10-25% is enough for providing sufficient daylight in Indian buildings. More over the concept of fully closed air-conditioned buildings if applied improperly/partly can have adverse impacts (5). Therefore, it is necessary to define the boundaries of truly passive buildings that provide thermal comfort without the use of air conditioning systems in the tropics.

Category of the action

Building efficiency: Physical Action

What actions do you propose?

Proposed Actions

  • Defining the boundaries to achieve passive buildings that provide thermal comfort without the use of conventional air conditioning systems in the context of developing cities in the tropics.
  • Identifying the scope and limitations of ‘such’ buildings and finding means to improve them in their own realm before converting them into complete air-conditioned buildings.
  • Developing practical benchmarks by addressing the technical, social and economic barriers in order to realize truly passive and low energy buildings.
  • The objective is to reinforce qualitative and empirical data from passive and low energy building techniques by validating them using the best computational technology available. The process of validation should find shortcomings and augment trustworthy methods to aiding the climate responsive design process of passive buildings in the present era.



The study aims to understand existing building typologies, techniques and develop effective ways to aid the design and benchmarking of passive and low energy buildings as opposed to closed air-conditioned buildings. A broad data collection and field analysis (where data is not already available) would be done in the geographical area of study studying various architectural and urban characteristics such as climate, building typologies, building materials, housing density, local building byelaws, land usage, building materials, housing density, etc. Key technical parameters that determine various typologies would be function, usage, occupancy, internal loads and thermal comfort, which have strong bearing on building energy consumption among other factors. Issues related to material supply chain, pace of construction and space requirements to incorporate passive design principles have economical bearing on construction industry. Therefore, understanding, re-adaptation of truly passive buildings from the pressures and vantage point of the society, infrastructure and economy thus becomes very important. The literature and field studies would then be distilled into two categories. The first one will focus on the state of the matters in building construction and technology and the second will focus on the past, existing, modern and innovative passive building techniques. The next step is to overlap both the data and identify critical gaps between them.

The passive design techniques obtained from the research data would be segregated into two levels. First level would be individual passive techniques and technologies based on principles or technologies such as e.g., shading, orientation, thermal mass, cross ventilation, ground coupled pre cooling of air etc. The second level would be combined packages of individual technologies suited for adaptation in different building typologies. Computational methods would be used to develop calibrated models from the selected tools to validate the data at both levels against the empirical data.

The data obtained at both levels is then critically analyzed against various technical, social and economic propositions of current buildings. Merits, demerits, applicability of passive technologies in various building typologies of the current era would be studied. The outcomes from the design and technical studies pave way to develop a novel approach of benchmarking the building efficiency called Passive Architectural Design Index (PADI). PADI establishes a critical threshold limit beyond which the usage of air conditioning in buildings becomes indispensable to achieve thermal comfort indoors. This study aims to develop a benchmarking based on “design approach” by the virtue of its passive techniques and technologies encouraging designers to be more ecologically responsible in the way they design.

PADI does not aim to be just design guidelines or codes, but also act as a reverse benchmark that precisely differentiates ‘sufficiency’ from ‘efficiency’. The exact nature of the benchmark is something that needs to be worked upon due course. Unlike energy benchmarks typically expressed as a measure of specific energy consumption, e.g., kWh/m2, PADI is a reverse benchmark (or may be a group of combined indicators) that define, a truly passive/seasonal/hybrid/closed building. To put it loosely, ‘PADI’ could be an indicator pointing out that in a certain climate or under certain weather conditions, a certain type of building with certain functions or internal loads could well be designed to operate freely without the use of air conditioning and still be able to provide thermal comfort to the inmates. This is in no way benchmark that restricts the architects the freedom to design. Rather this is to remind them the basics of design that the now tend to forget completely and let the ball roll to the domain of other professionals very comfortably. Architects should relieve themselves from this agony of designing highly insulated airtight boxes aka refrigerators posing as buildings in the name of energy efficiency. 

Further, the study looks into the use of different simulation tools at various stages of design such as dynamic simulation tools for detailed temperature and energy analysis, daylight simulation, and computational fluid dynamics for ventilation design etc. It helps in developing means to use these tools more intuitively rather than to limit them only for obtaining energy certifications. Where necessary, this research will discuss the process of integrating state of the art building simulation technology within the purposes of passive building design in order to assess the feasibility of efficient low energy and passive technologies such as earth air tubes, natural ventilation, double skin façade etc. or finding easy ways to design and validate novel project specific technologies.

Objectives and expected results

The research aims to present a set of techniques and technologies required to design and operate absolute passive buildings in a comprehensive format. Though this kind of literature exists in the form of different green building standards, textbooks, this research calls for the development and compiling of more localized, context specific, design intuitive database and technologies using the outcome of data analysis of the research.  At present there is a void of such kind of database that integrates design, evaluation and energy standards at the same time. The course of the study leads to establishing reliable methodologies to evaluate innovative passive and low energy techniques. This data can then be used to complement national standards like ECBC. This study should successfully open the domain of passive buildings to everyone. Then every other building designed can successfully incorporate trustworthy passive architectural features at its capacity. The main outcomes of the research includes:

  • To establish a benchmarking methodology called “Passive Architectural Design Index (PADI)”. PADI sets critical threshold limits beyond which passive building technologies alone are insufficient to ensure thermal comfort in the space and it becomes imperative to use air conditioning. PADI will be developed in the following four tentative categories.


  1. PADI – Absolute: For benchmarking buildings, which do not need mechanical cooling systems
  2. PADI – Seasonal: For benchmarking buildings, which need mechanical cooling systems operating only in peak season
  3. PADI – Hybrid: For benchmarking buildings, which have both conditioned and unconditioned zones at the same time
  4. PADI – Active: For benchmarking buildings, which are designed ‘closed’ and run on air conditioning all the time


  • Reinterpretation of the passive building guidelines and bio-climatic charts to aid the design of modern buildings in the context of various technical, social and economic factors of the present time.
  • The research also intends to deliver a model PADI tool that contains a comprehensive database of passive techniques and technologies to aid passive building design for select climates, geographical locations, and building types.



Literature Survey

  • Study architectural anthropology
  • Identifying critical technical aspects such as building envelope, internal heat gains, thermal comfort and indoor air quality, changes in microclimate, changing temperatures, etc.
  • Identifying critical social aspects such as usage patterns and occupancy schedules, perception of thermal comfort etc.
  • Identifying critical economic aspects such as speed of construction, value of the land, cost of building construction, building tenancy patterns, energy costs etc.
  • Prepare templates and guidelines required for filed studies, data logging and experiments
  • Representation and analysis techniques for data visualization
  • Identifying necessary tools for carrying out validation studies using computational analysis. E.g., Matlab, Energyplus, Ansys Fluent etc.


Scoping and field studies

  • Short listing buildings and prepare schedules for carrying out field studies
  • Arranging for necessary apparatus, modus operandi to conduct field studies


Data monitoring and recording

  • In-situ U-value calculation of building envelope
  • Usage patterns and schedules
  • Thermal capacity of building envelope in relation to A/C usage patterns
  • Indoor temperature, humidity, ventilation, infiltration
  • Perception of thermal comfort 

Data visualization and validation using computational analysis

  • Making calibrated building energy models from the data obtained from field monitoring
  • Analyzing thermal comfort and energy consumption scenarios for various building typologies using different geometry, materials and usage patterns


Benchmarking and developing PADI tool

  • Developing individual passive techniques and technologies and combined package of passive techniques and technologies
  • Arriving at benchmarks and quantitative design guidelines that enable the design of truly passive and low energy buildings
  • Developing an intuitive tool to enable easy use of PADI


Field testing and evaluation of buildings developed on PADI guidelines 

  • Developing procedures for standardized field monitoring and performance evaluation of pre documented or innovative passive techniques of various categories of PADI buildings. This helps in maintaing the database and dynamically adjust various key input factors that makes up PADI benchmark to reflect practical situation. 

Who will take these actions?

The actor constellation consists of the following key categories: 

  • Technical and research institutes
  • Government/Bureaucracy/Statutory bodies
  • Builders and developers
  • Architects, designers and consultants
  • Financial institutions 
  • Equipment Manufacturers
  • Promoters of energy and green building rating systems


Development and deployment of PADI involves conducting technical studies, conducting meetings with stakeholders for their inputs, conducting feasibility studies for deployment of the codes, conducting capacity building and training workshops for better understanding of PADI, adopting the new code into existing body of building codes and finally enforcing the codes.  

The technical research necessary in developing PADI should be carried out by universities and research institutes under patron-ship from relevant Government ministries and statutory bodies. The author is planning a research in the same field with a potential Indo-German technical collaboration.  

Statutory institutions like the Bureau of Energy Efficiency (BEE) can be responsible to formulate and enforce policies and standards (like the Energy Conservation Building Code of India) aimed at achieving high levels of energy efficiency using PADI. Institutions like The Energy and resources Institute (TERI) and consultants working in the field should get involved in capacity building, finding knowledge transfer mechanisms and providing technical assistance.

Developer and Builder associations like The Confederation of Real Estate Developers’ Associations of India (CREDAI) and confederations like Confederation of Indian Industries (CII) should take up promotional activities and programmes to ensure that PADI gets accepted among wide spectrum of buildings.

Financial Institutions should offer incentives like soft loans for projects contributing to energy savings through the use of PADI & efficient technology. Manufacturers play an important role by promotingR&D and rolling out products that meet and surpass the set standards. 

Where will these actions be taken?

Most appropriate area of action is in the tropics and sub-tropics where there is potential of applying passive building techniques, especially with focus on passive cooling strategies. There is a huge potential for such technologies to be adapted in high-growth economies of Asia, Africa and Latin America which fall under the said climatic zones. 

However, in the cold and temperate regions where stringent standards such as PassivHaus are already existing, there could be meaningful exchange of knowledge between PADI and other standards. 

How much will emissions be reduced or sequestered vs. business as usual levels?

This can be estimated only after detailed studies are conducted. However, to put in simple terms, as they say, the most energy efficient building is the one that has never been built, similarly, the most energy efficient technology is the one that has never been used (or perhaps, very very minimally used). PADI aims to effectively address and manage demand side of the building before relying on energy efficient equipment. 

What are other key benefits?

Passive, vernacular and low energy technologies develop more skilled work force in construction industry and promotes business and growth opportunities for small and medium scale enterprises producing such technologies.

What are the proposal’s costs?

Considerable resources are needed for the initial phase of the project in developing PADI and then keeping it up to date with regular performance evaluation. An estimate of ca €300,000 is required, bulk of which covers research costs, policy formulation, capacity building and implementation. 

  • Research costs: Assuming at least two full time researchers and research costs such as equipment, transport, experiments etc. for a period of 3 years - €250,000
  • Stakeholder meetings, Papers and posters in conferences and seminars - €10,000
  • Policy formulation - €25,000 
  • Capacity building and implementation: For conducting and organizing training programmes and workshops, implementing pilots - ca €50,000 

Time line

A total of 5-7 years is envisaged for complete fulfillment of the objectives of the proposal from research to implementation. 

  • The research phase by which PADI benchmarking will be established in a way as described in the methodology above: 3-4 years
  • Stakeholder meetings, performance evaluation, testing phase, adjusting and correcting PADI: 1 years
  • Capacity building and implementation phase: 1-2 years

Related proposals


  1. IEA. (2013). Transition to Sustainable Buildings - Strategies and Opportunities to 2050. Paris, France.
  2. ibid
  3. CEA. (September 2011). Load Generation Balance Report 2010-11. Central Electricity Authority.
  4. Sundarraja, M., Radhakrishnan, S., & Priya, R. (2009). Understanding Vernacular Architecture as a tool for Sustainable Built Environment. 10th National Conference on Technological Trends (NCTT09), (S. 249-255).
  5. Dhaka, S., Garg, V., Jain, V., & Mathur, J. (2011). EFFECT OF ENVELOPE PROPERTIES AND THERMAL ADAPTATION ON ENERGY CONSUMPTION AND COMFORT CONDITIONS THROUGH SIMULATION OF VARIOUS ECMs. 12th Conference of International Building Performance Simulation Association,, (S. 1631-1638). Sydney.


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Ahuja, R., & Rao, V. (2005). Natural Cooling of Residential Buildings in Hot-Dry Climate. ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING) (6), 101-111.

BEE. (2007). Energy Conservation Building Code. Bureau of Energy Efficiency.


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