Elements or Components of Green Building-Material, Water, Energy Health

A green building has four main elements or components on which it is designed: materials, energy, water and health to make green building more sustainable.

Elements of Green Building Design

Following are the components of a Green Building to make it sustainable:

1. Materials for Green Building

Materials for a green building are obtained from natural, renewable sources that have been managed and harvested in a sustainable way; or they are obtained locally to reduce the embedded energy costs of transportation; or salvaged from reclaimed materials at nearby sites.

Materials are assessed using green specifications that look at their Life Cycle Analysis (LCA) in terms of their embodied energy, durability, recycled content, waste minimisation, and their ability to be reused or recycled.

 Fig: Parasoleil Recycled Content Panels

Fig: Chocolate bamboo

2 Energy Systems in Green Buildings

Passive solar design will dramatically reduce the heating and cooling costs of a building, as will high levels of insulation and energy-efficient windows. Natural daylight design reduces a building’s electricity needs, and improves people’s health and productivity.

Green buildings also incorporate energy-efficient lighting, low energy appliances, and renewable energy technologies such as wind turbines and solar panels.

2.1 Passive Solar Design

Passive solar design uses sunshine to heat, cool and light homes and other buildings without mechanical or electrical devices.  It is usually part of the design of the building itself, using certain materials and placement of windows or skylights.

2.1a) Rules Of Passive Solar Systems

• The building should be elongated on an east-west axis.
• The building’s south face should receive sunlight between the hours of 9:00 A.M. and 3:00 P.M. (sun time) during the heating season.
• Interior spaces requiring the most light and heating and cooling should be along the south face of the building. Less used spaces should be located on the north.

2.1b) The Advantages Of Passive Solar Design

• High energy performance: lower energy bills all year round.
• Investment: independent from future rises in fuel costs, continues to save money long after initial cost recovery.
• Value: high owner satisfaction, high resale value.
• Attractive living environment: large windows and views, sunny interiors, open floor plans.
• Low Maintenance: durable, reduced operation and repair.
• Unwavering comfort: quiet (no operating noise), warmer in winter, cooler in summer (even during a power failure).
• Environmentally friendly :  clean, renewable energy doesn’t contribute to global warming, acid rain or air pollution.

2.2 Passive Solar Heating

The goal of all passive solar heating systems is to capture the sun’s heat within the building’s elements and release that heat during periods when the sun is not shining. At the same time that the building’s elements (or materials) is absorbing heat for later use, solar heat is available for keeping the space comfortable (not overheated).

2.2a) Two primary elements of passive solar heating are required:

• South facing glass
• Thermal mass to absorb, store, and distribute heat.

2.2b) There are three approaches to passive systems

1. Direct Gain: Sunlight shines into and warms the living space.
2. Indirect Gain: Sunlight warms thermal storage, which then warms the living space.
3. Isolated Gain: Sunlight warms another room (sunroom) and convection brings the warmed air into the living space.

3. Water Management in Green Building

Minimising water use is achieved by installing greywater and rainwater catchment systems that recycle water for irrigation or toilet flushing; water-efficient appliances, such as low flow showerheads, self-closing or spray taps; low-flush toilets, or waterless composting toilets. Installing point of use hot water systems and lagging pipes saves on water heating.

3.1) Rainwater Harvesting in Green Building

Rainwater harvesting is the principle of collecting and using precipitation from a catchments surface.

An old technology is gaining popularity in a new way. Rain water harvesting is enjoying a renaissance of sorts in the world, but it traces its history to biblical times.

Extensive rainwater harvesting apparatus existed 4000 years ago in the Palestine and Greece. In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rain water to augment water from city’s aqueducts.

3.2) Rainwater harvesting is essential

Surface water is inadequate to meet our demand and we have to depend on groundwater. Due to rapid urbanization, infiltration of rainwater into the subsoil has decreased drastically and recharging of groundwater has diminished.

As you read this guide, seriously consider conserving water by harvesting and managing this natural resource by artificially recharging the system.

3.3) Rainwater Harvesting Techniques for Green Buildings

There are two main techniques of rainwater harvestings.

1. Storage of rainwater on surface for future use.
2. Recharge to groundwater

3.3.a) Storage of rainwater on surface for future use.

The storage of rainwater on surface is a traditional techniques and structures used were underground tanks, ponds, check dams, weirs etc.

3.3.b) Recharge to groundwater

Recharge to groundwater is a new concept of rainwater harvesting and the structures generally used are Pits ,Trenches, Dug wells, Hand pumps, etc.

4. Health Components of Green Building

Using non-toxic materials and products will improve indoor air quality, and reduce the rate of asthma, allergy and sick building syndrome. These materials are emission-free, have low or no VOC content, and are moisture resistant to deter moulds, spores and other microbes.

Indoor air quality is also addressed through ventilation systems and materials that control humidity and allow a building to breathe.

In addition to addressing the above areas, a green building should provide cost savings to the builder and occupants, and meet the broader needs of the community, by using local labour, providing affordable housing, and ensuring the building is sited appropriately for community needs.

WHAT MAKES A BUILDING GREEN? – GREEN BUILDING CONCEPT

The green building concept is gaining importance in various countries. These are buildings that ensure that waste is minimized at every stage during the construction and operation of the building, resulting in low costs according to the experts in the technology.

Green buildings are designed to reduce the overall impact of the built environment on human health and natural environment by:

• Efficiently using energy, water and other resources.
• Protecting occupant’s health and improving employee productivity.
• Reducing waste, pollution and environment degradation.

Following examples can be considered for green buildings:

• Green buildings may incorporate sustainable materials in their construction (e.g., reused, recycled content, or made from renewable resources).
• Create healthy indoor environments with minimal pollutants (e.g., reduced product emissions).
• And feature landscaping that reduce water usage (e.g., by using native plants that survive without extra watering).
• A green building is a structure that is environmentally responsible and resource-efficient throughout its life-cycle. These objectives expand and complement the classical building design concerns of economy, utility. Durability and comfort.

Fig: Components of a green building

What are green features of a green building?

• Minimal disturbance to landscapes and site condition
• Use of non-toxic and recycled / recyclable material
• Efficient use of water and water recycling
• Use of energy efficient and eco-friendly equipments
• Use of renewable energy
• Quality of indoor air quality for human safety and comfort
• Effective controls and building management systems

GREEN ROOFING – A STEP TOWARDS SUSTAINABILITY

A green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems. (The use of “green” refers to the growing trend of environmentalism and does not refer to roofs which are merely colored green, as with green roof tiles or roof shingles.)

Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs, although this is an area of debate. Rooftop ponds are another form of green roofs which are used to treat greywater.

Also known as “living roofs”, green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures and combat the heat island effect.

There are two types of green roofs: intensive roofs, which are thicker and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are covered in a light layer of vegetation and are lighter than an intensive green roof.

The term green roof may also be used to indicate roofs that use some form of “green” technology, such as a cool roof, a roof with solar thermal collectors or photovoltaic modules Green roofs are also referred to as eco-roofs, oikosteges, vegetated roofs, living roofs, and greenroofs.

Figure: Cross-section of a green roof

Fig: Traditional sod roofs can be seen in many places in the Faroe Islands.

Fig: Green roof of City Hall in Chicago, Illinois.

Types of Green Roofs

Fig: An intensive roof garden in Manhattan

Green roofs can be categorized as intensive, “semi-intensive”, or extensive, depending on the depth of planting medium and the amount of maintenance they need. Traditional roof gardens, which require a reasonable depth of soil to grow large plants or conventional lawns, are considered “intensive” because they are labour-intensive, requiring irrigation, feeding and other maintenance.

Intensive roofs are more park-like with easy access and may include anything from kitchen herbs to shrubs and small trees. “Extensive” green roofs, by contrast, are designed to be virtually self-sustaining and should require only a minimum of maintenance, perhaps a once-yearly weeding or an application of slow-release fertilizer to boost growth.

Extensive roofs are usually only accessed for maintenance. They can be established on a very thin layer of “soil” (most use specially formulated composts): even a thin layer of rockwool laid directly onto a watertight roof can support a planting of Sedum species and mosses.

Another important distinction is between pitched green roofs and flat green roofs. Pitched sod roofs, a traditional feature of many Scandinavian buildings, tend to be of a simpler design than flat green roofs. This is because the pitch of the roof reduces the risk of water penetrating through the roof structure, allowing the use of fewer waterproofing and drainage layers.

Environmental Benefits:

Green roofs are used to:

• Reduce heating (by adding mass and thermal resistance value). A 2005 study by Brad Bass of the University of Toronto showed that green roofs can also reduce heat loss and energy consumption in winter conditions.
• Reduce cooling (by evaporative cooling) loads on a building by fifty to ninety percent
• especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir — a concentration of green roofs in an urban area can even reduce the city’s average temperatures during the summer
• Reduce stormwater run off
• Natural Habitat Creation
• Filter pollutants and carbon dioxide out of the air which helps lower disease rates such as asthma
• Filter pollutants and heavy metals out of rainwater
• Help to insulate a building for sound; the soil helps to block lower frequencies and the plants block higher frequencies
• If installed correctly many living roofs can contribute to LEED points
• Agricultural space

Financial benefits

• Increase roof life span dramatically
• Increase real estate value

A green roof is often a key component of an autonomous building.

Several studies have been carried out in Germany since the 1970s. Berlin is one of the most important centers of green roof research in Germany. Particularly in the last 10 years, much more research has begun. About ten green roof research centers exists in the US and activities exist in about 40 countries.

In a recent study on the impacts of green infrastructure, in particular green roofs in the Greater Manchester area, researchers found that adding green roofs can help keep temperatures down, particularly in urban areas: “adding green roofs to all buildings can have a dramatic effect on maximum surface temperatures, keeping temperatures below the 1961-1990 current form case for all time periods and emissions scenarios.

Roof greening makes the biggest difference where the building proportion is high and the evaporative fraction is low. Thus, the largest difference was made in the town center.