Towards Net Zero Energy (Part I)

With energy conservation and carbon reduction key priorities, it is in the collective interest of all to encourage Net Zero Energy Building as an imperative requirement. Where are we as far as this approach is concerned?

As per the latest annual energy statistics published by the Ministry of Statistics, Planning and Implementation; Residential and commercial structures consumed nearly 32 per cent – one-third of the country’s total electricity consumption in 2016. Naturally, as Cities grow; building energy demand is bound to surge correspondingly.

In the US, buildings consume 70% of total Energy Consumption, emitting over one-third of US Green House Gas emissions, which is more than any other sector of the US Economy.
Energy use, the associated Carbon Footprint, with its adverse impact on People and the Planet, leading to Climate Change, have cast a sharper focus on the need for updating technology from time to time.

The international community has clearly defined climate change as a priority and an opportunity to shift focus towards a Low Carbon economy, in the global context too.

The Paris Agreement, adopted in December 2015 under the United Nations Framework Convention on Climate Change (UNFCC), is a commitment to accelerate and
intensify the actions and investments needed for a sustainable low carbon future, to limit global average temperature rise to well below 2 degree C above pre-industrial levels, and to pursue efforts to limit the increase to 1.5 degree C.

With energy conservation and carbon reduction key priorities, it is in the collective interest of all to encourage Net Zero Energy Building as imperative requirement.

Indian government’s Policy Agency, Niti Aayog, estimates that energy demand from India’s buildings will increase by more than 800 per cent in 2047 compared to 2012.

Under the current standards, the country will face higher energy costs and skyrocketing consumption for decades, air pollution will worsen, adding to the impact of climate change. Hence, India needs better building efficiency policies and programs now.

Existing Building Energy Efficiency

For achievement of Energy Efficiency in existing buildings, the following points are important:-

  • Reduce consumption of Energy, by following simple disciplines such as switching off Lights, Fans and other appliances, when not needed.
  • Replace old appliances such as fans, refrigerators, air- conditioners, lighting etc. with better energy efficient BEE Star rated appliances. With consequent reduced electricity bills, and better Pay Back returns, the investment is justifiable.
  • For Commercial Buildings with over 100 kW of connected loads, it is mandatory to conduct Energy Audit as per Energy Conservation Act 2001, and scope for Energy Star Rating of BEE.
  • Reduction in consumption of water, to solve acute water scarcity, added to the associated energy use for pumping and distribution of water.

Nnumerous Schemes from the Govt

(Implementable, either mandatorily or voluntarily)

Energy audit: Studies in buildings have shown large potential for energy savings both in government and commercial office buildings.

Star rating of buildings: The Bureau of Energy Efficiency (BEE) has developed a scheme for energy efficiency labelling of Buildings, in February 2009. The star rating of building is aimed at accelerating energy efficiency activities in commercial buildings across
the country.

The Star Rating Programme would provide public recognition to Energy Efficient Buildings, thus creating a market demand for such buildings. This programme would rate buildings on a 1-5 Star scale with 5 Star labelled buildings being the most efficient. BEE Star Rating Scheme is based on actual performance of the building in terms of specific energy usage termed as Energy Performance Indicator (EPI).

Energy Performance Assessment of Existing Buildings

Energy Performance Index (EPI) – Average Annual Hourly EPI. (EPI = Total kWhr/Surface Area AAHEPI=EPI/Hours Working) with, Assessment of (1) Cooling Loads from a Building (2) HVAC System and (3) Lighting System

Assessment of the energy saving potential

  • Ratings apply to buildings with a connected load of 100 kW or a contract demand of 120 kVA, whichever is greater and are intended to be used for commercial purposes.
  • The programme covers five categories of commercial buildings, Office buildings, Hotels, Hospitals, Retail malls and IT parks in four Climate Zones across the country.
  • Buildings in climatic zones namely Warm and Humid, Composite, Hot and Dry, Temperate regions are being currently rated.
  • Criteria indicating EPI value and corresponding Star Label under the various climatic zones (for buildings having air conditioned area greater than 50% of their built up area & for buildings having air conditioned area less than 50% of their built up area) are referred for assigning Star Label.

Office Building Rating

  • EPI shall be kWh/sq.m/year in terms of Purchased & Generated Electricity divided by Built up Area in sq.m
  • The total electricity should not include electricity generated from on-site renewable sources such as solar photovoltaic etc.

B P O Offices

EPI shall be Average Annual hourly Energy Performance Index (AAhEPI) in (Wh/hr/sq.m), which is Purchased & Generated Electricity, divided by Built up Area in sq.m and Total Annual Hours of Operation. The total electricity should not include electricity generated from on-site renewable sources such as solar photovoltaic etc.

Energy Conservation Building Codes

  • Currently, Energy Conservation Building Codes (ECBCs) exist to help guide designers, architects, builders and contractors achieve more energy efficient and sustainable buildings than in years past.
  • Launched by BEE in 2007, updated in 2017 to match with the technology developments to set higher bench marks of Energy Efficiency.
  • Objective is to ensure: –
  • Energy efficient design, retro fitment without compromising comforts, health, productivity, economy
    -Apply local conditions, improve condition
    -Emphasis on Integrated Building Design
    -Encourage continuous improvisations

ECBC Compliance Approaches

-Mandatory Requirements
-Prescriptive Method
-Whole Building Performance Methods
-Energy Simulation with Design Builder software

Impact of ECBC compliance

-Lower HVAC loads – Reduced consumption/cost
-Lesser addition of power generation capacity
-Better building performance
-Climate oriented design practice such as:
-Improved lighting and extensive use of day lighting
-Use of natural ventilation / Free cooling system
-Market demand of energy efficient Products like Glass, Insulation, Insulation, HVAC Equipment etc.

Green Buildings – Sustainable Buildings

A Green Building is a building that, in its design, construction or operation, reduces or eliminates negative impacts, and can create positive impacts, on our climate and natural environment. Green buildings preserve precious natural resources and improve our quality of life, based on sustainable development concepts increase the efficiency of resources :-

-Waste generated
-Less transportation use
-Better living conditions
-Habitat protection and restoration, while reducing the impact the construction project has on humans, health, and the environment
-Efficient use of energy, water and other resources
-Use of renewable energy, such as Solar , Wind, Bio Mass
-Pollution and waste reduction measures, and the enabling of re-use and recycling
-Good indoor environmental air quality
-Use of materials that are non-toxic, ethical and sustainable
-Consideration of the environment in design, construction and operation
-Consideration of the quality of life of occupants in design, construction and operation
-A design that enables adaptation to a changing environment

Management of Green Buildings – Steps Involved

-Operation, maintenance
-Waste removal/disposal
-Green building leads to
-Reduction in operating costs by increasing productivity
-Using less water and energy
-Improve health by improving indoor air quality
-Reduce environmental impacts

Importance of Embodied Energy in Selction of Sustainable Materials Embodied energy

-The total energy required for extraction, processing, manufacture and delivery of building materials to the building site
-Energy consumption produces CO2, which contributes to greenhouse gas emissions
-The Embodied Energy is an indicator of the overall environmental impact of building materials and systems, a deciding factor as to whether a product contributes to mitigates global warming

Important Points to Note on Embodied Energy

-The total amount of embodied energy may account for 20% of the building energy use.
-Reducing embodied energy significantly reduces the overall environmental impact of the building.
-Embodied energy must be considered over the lifespan of
a building.
-As the energy efficiency of building increases, the embodied energy of the building materials become increasingly important.

Measurement of Embodied Energy

Embodied energy is measured as the quantity of non-renewable energy per unit of building material, component or system. It is expressed in Mega Joules (MJ) or gigajoules (GJ) per unit weight (kg or tonne) or area (M21 Calorie =4.1858 Joule

The above Chart is self-explanatory as to the quantum of embodied energy and selection of each and every Green Building Construction Material to enable Design and Construction.
(To be continued to the next issue)

G Harihara Iyer
The author is a Fellow of the Institution of Engineers, a Certified Energy Auditor and a Lead Auditor for Energy Management System ISO 50001. He is also a Graduate Member of the All India Management Association, a Life Member of the Mining Engineer’s Association of India and a Life Member of the Orissa Engineering Congress.

Leave a Reply