Role of Glass in Green Architecture

Role of Glass in Green Architecture

Green building design criteria emphasizes the energy-efficient performance of fenestration materials and maximum use of natural daylight. Given this background, Glass is an indispensable material for green building. It has a wide range of functional benefits. Its transparency allows day-lighting of the interiors and integrates the interiors with the exteriors. Studies have proven time and again that this substantially improves the productivity and health of the occupants of the building.

Glass is completely recyclable and non-toxic in nature. It satisfies all the ecological parameters of being the most sought after “green” building material in Green Buildings. Moreover it harmonizes a structure with its environment.

Glass has varied “Green” benefits of which, some of them are:

1. Day-lighting - The use of glass brings in lot of light that helps in giving a high amount of natural day lighting instead of depending solely on artificial lighting thus reducing considerably electricity consumption.
2. Blending interiors with exteriors (Views) - Glass facades give a spectacular view of the outside world from the cozy interiors.
3. Recyclability - Glass being recyclable satisfies the important parameter of being a “Green” building material.
4. Achieving energy efficiency - High performance glass helps in controlling the solar and thermal heat in the interiors and helps to maintain the temperature at its minimum best and in turn helps to tone down the air-conditioning expenses.
5. Innovative application - Being very flexible building material glass helps to satisfy and capture an architect's utmost imagination in its shape and form.
6. Controls noise: Double glazed glass facades help in achieving a high degree of acoustic comfort by keeping away noise penetrating from the exteriors to the interiors thus ensuring a calmer atmosphere inside.
7. Self Cleaning: The future belongs to self-cleaning glass which keeps itself clean on its own and brings out an ever sparkling effect.

Glass and LEED Rating

The Leadership in Energy and Environmental Design (LEED) Green Building Rating System, developed by the U.S. Green

Building Council (USGBC), provides a suite of standards for environmentally sustainable construction.

The LEED rating system for Green buildings has six major areas of which four have the potential to be tapped through

appropriate usage of High Performance Glass in design:

ENERGY & ATMOSPHERE (EA)

Optimize Energy Performance

The building facade, windows, doors, and skylights can be designed with high performance glass to meet the desired solar  heat gain  coefficient and U-value  requirements.  The  use  of  glass  can  let in  adequate  daylight resulting  in reduction of artificial lighting costs. A complete energy simulation for the building is possible nowadays and helps to improve the energy performance of the design.

MATERIALS & RESOURCES (MR)

Regional Materials

The distance from the glass manufacturing/fabrication facility to the job site (within 500 miles radius) is a major factor in gaining points under the Regional Materials Credit. The wide network of Saint-Gobain Glass' processors and fabricators helps under this category.

INDOOR ENVIRONMENTAL QUALITY (EQ)

Daylight and View

High Performance glass from Saint-Gobain helps to blend the twin actions of achieving desired levels of daylight and transparency to enable external views. The letting in of natural light helps cut down on the artificial lighting costs.

INNOVATION & DESIGN PROCESS (ID)

Innovation in Design

Saint-Gobain  Glass  addresses  needs  such  as  Acoustic  Insulation,  Self-cleaning  etc  apart from  the  prescribed requirements of Energy Efficiency, Recyclability and Day-lighting. High performance glass when used in Double Glazed panels or as Laminated units provide higher degree of Acoustic Insulation that ward off unwanted noise from the external atmosphere. Saint-Gobain also offers Self-cleaning glass that can keep itself clean without any maintenance hassles.

Thus the overall innovative use of High Performance Glass from Saint-Gobain in a building can fetch upto 13% of the overall points in the LEED Rating system.

Choosing Glass

In tropical countries like India, one needs to be careful in selecting the right glass solution. Selecting the right kind of product is critical in maximizing the benefits possible from glass.

Broadly glass can be chosen according to the performance needs and the aesthetic needs. For a Green Building it is important to choose a glass solution that gives high performance without compromising on aesthetics.

PERFORMANCE CRITERIA

Optimum Light Transmission (LT)

As India is a tropical climate, we have abundant sunlight. Ironically the bill on artificial lighting contributes 20% to the total spend on electricity. The facts in reality are :

1.  The lux level from direct sunlight is around 1,13,000 Lux.
2. The lux level in shade is around 9,000 Lux.
3. Brightly lit interiors which are conducive for working require 500 Lux.

High Performance Glass helps in cutting down excessive glare and brings in abundant natural light thus reducing the dependence on artificial lighting.

Energy Efficiency

In climatic conditions like India, 80% of  the  total heat gain is due  to direct solar  radiation  and  the  rest is due  to temperature difference between the exteriors and interiors. Thus to reduce the overall Relative Heat Gain (RHG) in tropical  climates,  it becomes  necessary  to  curtail  the  incoming  solar  radiation  by  the  use  of  glass  with  high performance solar “control” coating. Contrary to this, in cold climates the emphasis is on glass with low-emissive coatings to reduce the rate of heat loss from interiors to exteriors.

The  total  heat gain  is  measured  in  terms  of  Solar  Factor  and  U-value  and  is  expressed  as  a  sum  of  these  two components.

Solar Factor

Heat gain on the inside of the building due to direct solar radiation incident on glass is measured through the solar factor of glass.

Solar  Factor:  It is  the  sum  of  percentage  of  incident solar  energy  directly  transmitted  and  incident solar  energy absorbed and re-emitted inside.

U-Value

Heat gain due to temperature difference is expressed by U-Value of a glass.

U-Value: It is the amount of heat transferred(lost/gain),due to a temperature differential of 1˚C between inside and outside per square meter.

The best energy performance is obtained from a glass solution which is lower in terms of Solar factor and the U-value. Thus the best option for tropical climates, is to use glass with high performance solar control coatings double glazed with low-emissive glass to reduce the overall heat gain.

AESTHETIC NEEDS

The  High  Performance  Energy  efficient glass  solutions  from  Saint-Gobain  have  also  been  categorized  under  the various Houses of Color to enable comparison of the products based on aesthetic considerations.

The Houses of Color are:

1. Neutrals
2.  Metals
3.  Blues
4.  Greens
5. Blue-Green

Shortly, India would have stringent regulations to conserve energy by way of the Energy Conservation Building Code (ECBC) that would impact upcoming buildings and buildings going in for renovation. Saint-Gobain Glass has a wide range of ECBC Compliant products.