Towards Net Zero Energy Building PART – III

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?

Net or nearly Zero-Energy Buildings (NZEB) have very high performance. The low amount of energy need comes mostly from renewable sources, producing as much energy as they consume, accounted for annually.

-Net zero energy goals aim at reducing energy demand using energy efficient, technologies, utilizing renewable energy sources to meet the residual energy demand in such buildings. Efficiency gains enable the balance of energy needs to be met by renewable energy technologies.
-NZEB is aimed at eliminating Greenhouse Gas (GHG) emissions associated with the operation of new buildings by 2030, and eliminate the GHG emissions from all buildings by 2050.
-Both active and passive measures along with energy generation/supply from renewable energy such as Solar Photovoltaic, Winds, Biogas, and any other applicable hybrid renewable energy system.

(BEE) Nearly Zero Energy Building (nZEB)

A building having an Energy Performance Index (EPI) of less than 15 kWh/m2/ Year is classified as Nearly Zero Energy Building. Minimum Requirement for specified Building for assessment is 5000 < Sq. M, with connected Load of 100 kW and Contract Demand of < 120 kVA.

Net Zero Energy Building:  NZE Building should have 0 kWH Net Zero Energy Building (NZEB) is a method of design and construction that aims to achieve an energy efficient, grid-connected building, enabled to generate energy from renewable sources to compensate for its own energy demand.

As a result, these buildings have Net Zero energy consumption, such that the total energy used by the building on an annualized basis is equal to the amount of renewable energy created on the site or at a nearby location.

Zero Energy Building, the Ultimate Goal

ZEB is a combination of closely-integrated evolving technologies such as renewable energy sources, heat pumps, high efficiency windows and insulation, and solar panels, wind power. These buildings consequently reduce energy consumption protecting our environment for future generations. In short they reduce:

-Energy consumption,
-Green House Gases (Carbon Emissions) leading to Global Warming
-Dependence on Fossil Fuels

Concept of a Zero-Energy Building (ZEB), or Zero Net Energy (ZNE) Building…

Design Steps

Site selection, Orientation, layout and location on site will all influence the amount of sun a building receives and therefore its year-round temperatures and comfort:

-Be  flat or north-sloping , free of obstructions to the north, be able to accommodate a building with a relatively large north-facing wall or walls for maximum solar gain, as well as north-facing outdoor areas.
-Reduce Heating, Cooling, and Lighting Loads through Climate Responsive Design and
Conservation Practices.
-Employ Renewable or High Efficiency Energy Sources.
-Passive solar design – In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. Unlike Active Solar heating systems, Passive does not involve the use of Mechanical and Electrical devices.
-Solar panels are placed on the rooftop or windows of the building, or anywhere where maximum solar energy is received throughout the year.  The energy generated can be used for cooking, heating, generating electricity etc.
-Use of thermal mass and phase-change materials for slowing indoor air temperature swings, solar cookers, the solar chimney for enhancing natural ventilation, and earth sheltering.
-Wind as a renewable source of energy–In some extreme areas where wind energy is abundant and high, small windmills can also be used to generate electricity for running Building envelope design.
-Use high performance building envelopes select walls, roofs, and other assemblies based on long term insulation, air barrier performance, and durability requirements, such as, damp proofing, waterproofing membranes, insulation materials, water stops,  drainage pipe.

Zero Energy Building Advantages

-Increased comfort due to more-uniform interior temperatures
-Reduced requirement for energy
-Reduced total cost of ownership due to improved energy efficiency
-Reduced total net monthly cost of maintenance

Net zero energy building is one of the solutions to reach energy and carbon reduction targets. Net Zero Energy Buildings are striving today for a better tomorrow.




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.

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