Architectural Design for Green Buildings

British architect John Pawson once said, ‘Architecture isn’t just about creating new buildings. Sometimes, it’s about returning what’s already there.’ Green architecture promotes using environmentally low-impact materials and methods to create structures that are energy efficient, aesthetically attractive, blends with the environment and does not harm the habitat. A great variety of buildings can be constructed this way, from using natural materials, solar panels, incorporating natural greenery into architectural drafting and design to recycling water and more innovative processes. Besides the low environmental impact of a building, indoor air quality and efficient water and energy conservation are key factors for a truly green structure.

Green design is also known as sustainable development, eco-design, eco-friendly architecture, and some even throw the term ‘arcology’ around. Whatever people call it, green architecture promotes nature and espouses organic practices in architecture. Architects have even used the term ‘biomimicry’ to guide green design. Mimetic architecture, as the name suggests, is a form of architecture that mimics its surroundings. An example of biomimicry is the Venezuelan Pavilion at Expo 2000. Just as a flower looks and behaves, petal-like awnings could be adjusted to control the interior environment.

In a time of global climate change, the earth must adapt quickly to prevailing and ever-changing environmental conditions. The construction industry recognises its contribution to greenhouse gases. It is believed that cement manufacture is one of the largest global contributors to carbon dioxide emissions. Architects, such as Edward Mazria, have said, ‘All new buildings, developments and major renovations shall be carbon-neutral by 2030.’ A noble goal, but how can green architecture help?

Architectural design for green buildings is fundamentally about incorporating structural design and MEP systems design into the architectural framework to produce a finished product that enriches its surroundings. There are a number of ways this can occur.

Green Roofs

We’ve all heard of a green roof, but what is it exactly? A green roof is a rooftop garden, lawn or space that is host to a variety of trees, plants and grass. Some of the most useful advantages of a green roof is the fact that it can lower the temperature in an entire house, improve air quality, create urban lungs and simply look lovely. It has been known to attract several species of birds as well.

There are two kinds of green roofs – extensive or intensive. The extensive green roof uses less soil and is low maintenance. An intensive green roof uses greater soil depth, which can host a greater variety of plants and even trees, but which will require frequent maintenance and care. These roofs can be a simple mix of ground-covering greenery or they can include exotic plants, moss, herbs and small fruit trees. Green roofs help insulate the roof from the blistering heat of tropical summer suns, filter rainwater and help fight against habitat depletion.

Creating a Green Roof

• Lay a waterproof barrier on the roof.
• Top it with material for drainage.
• The topmost layer consists of soil and low-maintenance plants.

Solar Panels

Though solar panels save conventional energy sources and reduce expenditure, they can be visually unappealing. Innovative concepts, such as solar shingles, may change the face of solar panels. Typically, solar panels are placed on top of the roof or on a free-standing structure near the building. Solar shingles are part of the roof, thus less obvious and less of an eyesore. Though more expensive than solar panels, solar shingles are actual shingles that power the building. Thin-film shingles cost less and produce less energy per square foot than silicon-based shingles. All solar shingles are wired into the electrical system and must be at the correct angle to absorb optimum levels of sunlight. Solar shingles become more hot than solar panels.

Cob

Natural materials, such as cob, create interesting visuals while maintaining a low carbon footprint. Used from ancient times, cob is fundamentally wet earth mixed with straw, which is then rolled into brick-like pieces and stacked together to construct homes. Similar to clay, cob houses generally exhibit unique organic shapes. Once individual cob pieces are stacked, the cob material is used to hand-mould the walls. This process results in curving structures and houses can have built-in shelves, nooks and furniture, such as couches and tables.

Rainwater Harvesting - Much like an urn or fountain, rainwater harvesting systems are connected to underground containers that collect, store and use the harvested water without marring the landscape. Harvested rainwater is generally used to irrigate gardens but can be sometimes used within the home.

Shipping Containers - As strange as it may seem, shipping containers have been used to create homes. Rather than use new raw materials, old shipping containers are used as prefabricated structures. These containers can be stacked on top of each other or side by side to create both residential and commercial buildings. Prefab shipping container homes can be equipped with electrical, plumbing and even central heating or ventilation systems.

Besides opting for eco-friendly materials and construction methods, a ‘green’ architect strives to create building design that goes further than the basic standards set by codes. They attempt to improve building performance and minimise long-term environmental impact and cost. Full sustainability is one of the prime objectives of green buildings. Here’s how it can be achieved:

Key Features of a "Green" Building

• 1. Ventilation systems - efficient heating and cooling design
• 2. Lighting and appliances are energy efficient
• 3. Plumbing fixtures are designed to save water
• 4. Landscaping includes native vegetation
• 5. Maximum possible solar energy collection
• 6. Use of alternative renewable energy sources - wind power
• 7. Natural, non-toxic material used for interiors and exteriors of building
• 8. Locally obtained wood and stone, reducing long-distance transport
• 9. Harvested trees replaced by planting saplings
• 10. Innovative use of old structures
• 11. Recycling of architectural features
• 12. Intelligent use of space
• 13. Positioned on site to maximise sunlight, winds and take advantage of natural shelters
• 14. Rainwater harvesting and greywater reuse
Examples of Green Buildings
• There are many examples of innovative green buildings from around the world. A few are listed below:

California Academy of Sciences, San Francisco - Italian architect Renzo Piano created a green roof and recycled blue jeans as wall insulation in his design.

Olympic Village, London – Waterways were dredged, concrete was recycled and used rail and water for material delivery.

Crossway Zero Carbon Home, UK - Architect Richard Hawkes designed one of the first zero carbon houses in the UK. Featuring a timbrel vault design, it uses solar energy to generate its own electricity.

Sustainable House, Geul River, Netherlands – Raised on tree trunks in case of flooding, using charred wood cladding to reduce maintenance, this house sits on the banks of the Geul River. A traditional Japanese technique was employed to burn the cedar cladding panels, creating a sealed surface to protect the house and reduce repairs. Solar energy is used for heating and electricity. Waste water is filtered before allowing it into the river, and prefabrication was used for speedy construction.

Sustainable Architectural Concepts

Some of the green architectural concepts that can be implemented easily and planned early in the design process are:

• Open Rainscreens - Open rainscreens allow air in through sidings, removing stagnant air and moisture and keeping existing hot or cold air from escaping through the insulation.
• Natural Materials for Siding - Natural materials for siding, roofing and on the deck minimises the carbon footprint. Wood cladding on the exterior helps the building blend into any tree canopy.
• Outdoor Community Spaces - Locally sourced modified wood can be used for deck spaces and raised benches in open spaces to reinforce the link with nature.
• Green Roofs - Green roofs can be created on flat roofs. Green roofs reduce the impact of continuous direct sunlight and helps keep the building cool, reducing the use of cooling systems.
• Efficient LED Lighting - Large, intelligently placed windows can bring in natural light, and LED bulbs reduce energy wastage.
• Innovative Use of Traditional Materials - To make a building structurally sound, sustainable wood planks are bolted together in a hexagonal pattern, optimising floor space.
• Wooden Pool Decks - Water naturally drains through wooden slats on a pool deck, reducing slippage.

The Curious Case of the ‘Green’ Circle

Typically, houses aren’t round. Strangely enough, it is now widely acknowledged that the circular floor plan is the most efficient form for space usage. A round floor area has less wall length and uses less materials.

Curved walls need not be expensive. A series of low-cost, well-insulated prefabricated wall panels define the round wall appearance. Low maintenance siding or stucco can be used. No-maintenance stone or brick siding looks good too. Round walls can feature windows, decks, porches, balconies and cathedral ceilings. Since there are no interior support walls, room layouts can be changed frequently.

A circular house with the same square footage of interior space as a rectangular house has 20% less exterior wall area, cutting down on material usage, labour and costs. Less exterior wall space means that there is less need for heating and cooling. Winter winds flow around the outside without seeping in as drafts. Hurricanes and tornados are better resisted with a circular design. Windows can be placed at convenient angles to allow for effective cross ventilation in a circular space, and a roof in a pagoda style will function as a natural exhaust for warm air in summers.

Green architecture has to be part of the design process from the onset. Green design must be comprehended, analysed and effectively applied before construction. Aesthetics, cost, functionality, preservation, comfort, safety and sustainability must be considered early on.To a significant extent, architectural BIM modelling and architectural drafting enable this. A beautiful building, using expensive material, may not be ‘green’. Similarly, a ‘green’ building may be visually unappealing. For effective green architecture, much as the Roman architect Vitruvius said, a building must be built well, serve a purpose usefully and be beautiful. Architectural BIM modelling facilitates the viewing and analysis of modern structures to fulfil these design concepts.

Kuldeep Bwail, Director at XS CAD, providing 3D Architectural Modelling,3D BIM Modeling to Homebuilder, Architect