Design for Sustainability

Abstract

This article addresses sustainability in construction managed during design. Sustainability has number of definitions, among them is “meeting the needs of the present without compromising the ability of future generations to meet their own needs” by Brundtland Commission.

It is explained how proper management in design stage of the project can help providing sustainable structures. How appropriate planning can influence the construction sustainability? Early integration of construction planning can detect and eliminate problem sooner, cheaper and most importantly not charming the environment.

Construction works leave behind solid waste, that contributes to landfill and pollution. Some of the materials delivered on the site are never used and disposed immediately. Planning of the works in the initial phase of the project could bring better results in overall sustainability. Optimised delivery of new constructions are discussed.

Operation phase is also influencing sustainability. The initial choice of the energy source has a huge impact as well as user pattern, e.g. energy and water use. Here come many challenges like resource, waste management.

Demolition has even greater impacts than construction. Enormous volume of waste is generated. Proper choice of materials for the construction would result in more efficient utilisation of them in demolition or refurbishment.

It is discussed why cross-discipline team should be involved at the earliest stages of the project. Sustainable design principles are described as well as application of sustainability decisions during design.

Application

This section describes how design for sustainability applies on the example of building construction. Considerations on sustainability are presented in following stages of project life:

Pre-design

Designers must know the client might not have enough information about possible sustainable solutions. It is important that design team introduce those tools and possible benefits of using them to client during briefing process. Having that knowledge client is able to make better decision on the order he/she makes.

Prior actual design, appropriateness of the project must be evaluated. The site and local situation like resources available or existing structures as well as natural environment should be reviewed. E.g. perhaps there is already structure on the site that could be used or rebuilt or some of those components could be reused to create new building. It should be assessed whether the project is rational. Possibilities on sustainable construction in the localisation should be investigated, for instance local renewable energy sources or government support for green energy production.

Before starting the design, it should be assured that proper people are chosen for the project. The team of managers, designers and contractors should be aware of the sustainable targets of the project and work together from the first stages to achieve the goal.

Initial planning

After gaining knowledge on the local conditions it is time to implement proper strategies. The consideration on this stage is building positioning on the site. It must be done in such a way to ensure maximal utilisation of passive design strategies and minimise impacts on local fauna and flora. It is also important to consider how the connections to media (water, electricity) are located on the plot and how to utilise sun conditions and what will be the access to the construction site and building afterwards. Another important aspect of the design is influence on neighbourhood, if the structure will put shadows on other buildings, generate pollutions and what visual appearance it will have. The influence on surroundings should be considered for both construction and operation period.

In this stage, a discussion appears how to reuse or recycle locally available resources. E.g. on the site there is an old brick house, that will be demolished. How the brick could be reused in new construction? Here is where cooperation between architect and structural engineer should start. They need to agree if the bricks will serve as load-bearing structure, where they will be placed, if the structure will be visible or not (aesthetics).

Concept design

Further development of the design brings more sustainability issues to concern. The orientation of the building influence inner conditions like daylight availability or natural ventilation. External envelope must be designed carefully to ensure good thermal performance of the building. For that reason, window shapes and sizes are also important. The distribution of the rooms will be influenced by orientation and shape of the structure. It is also important part to integrate all services in the building in the initial state of the design. As an example: early discussion on the layout of the mechanical systems and structural parts could result in decreased need for suspended ceiling height. That will decrease building height and so reduction of the initial investment cost as well as decreased of energy demand (less space to heat equals less heat needed).

Detail design

Material selection

Choice of the materials for the project has a great impact on the sustainability of the structure. It is relevant throughout all life cycle of the product. The impact on the environment starts form the extraction of raw materials to produce building materials. If the choice is brick for instance, the impacts depend on: how clay is extracted, how it changes the local site, if during production of brick there is a lot emissions, how much heat is used during process. Moreover, there are additional concerns: transportation of the product form factory to the site, what treatment it needs to be assembled to become a wall, how it influences building indoor climate during operation, what happens after disassembly, is it reused or goes to landfill. In the end there is a question to be answered by designer: is there other material that has less impact? Maybe it is possible to reuse already available material or perhaps it is possible to find new one that can be recycled after building life and still serve people for other purposes. Local material might be better choice as the significant impact from the products is transportation. Even though one product might seem more environmentally-friendly it bigger perspective it could turn out that importing the more sustainable material (i.e. bamboo) from distant part of world does not pay off in terms of sustainability. People spend more of their time inside than outside. All materials that are components of our homes, schools and work places could be emitting particles, that have possible negative impacts on humans. The proper choice of materials influence health and well-being. For instance, concrete helps to keep lower carbon content in the air. Physical properties of materials are also relevant. Some of them might need to be replaced several times during building operation. It is a good question to be asked whether it is better to use longer lasting substitution. It must be also mentioned that thermal mass of materials can significantly enhance thermal performance of the building. Depending on the material sizes and characteristics it might need special equipment for the construction purposes. Renting additional crane might be a solution, but does it pay off? Choice of the materials also influences the use phase. Some materials are easy to maintain, while others need special treatment. It could increase for instance water use for cleaning purposes. Another aim of the design could be to decrease amounts of material required for construction. One of the approaches id modularisation. Using typical sizes of the smaller structural elements can eliminate need for adjustments like cutting the tiles. In this way, there are no waste produced on the site.

Energy

There is a list of elements that influence energy performance of the building. The proper design and construction of building envelope has great impact on the energy demand. There should be chosen sufficient thickness of insulation and the building should be raised in the way that it is tight. Not only envelope is important but also choice of energy source, certainly solar heating system is more sustainable that coal furnace. Choice of artificial light type and bulbs used as well as appliances energy class are contributing to overall sustainability of the building. Daylight design has also influence on the building. There are solar heat gains and heat loses through glazing. Depending on the design, those could have positive or negative impacts.

Water

Water consumption is second after energy issue that impacts environment. To save water there are designed rainwater collection, greywater and back water systems. Those can significantly reduce building demand for water or even reduce it completely. It may seem that the tanks can be just added at the construction process. However early implementation into design can result in better water collection efficiency, for instance by dedicated roof design to gather more rainwater. Water efficient sanitary equipment chosen for the project can help reduce needs for water use. Depending on the location water might be very valuable resource, that is why right choices should be done as soon as possible.

Construction management

It may seem that nothing can be done while designing to ensure sustainability during construction works. Having discussed site challenges between designing team and construction managers is crucial. It may not only make worker’s life easier but also contribute to savings and most importantly save environment from the impacts of the works. Planning of the construction works should start with beginning of design process. The site conditions might determine some aspects of the construction works. In difficult lots, access to the construction site might determine location of the building. To ensure sustainability during the works, the construction manager should be aware of the amounts of the materials needed. Precise numbers provided by the architect can help to decide about quantities to be ordered and it will reduce number of left-overs. Recycling on the site will also contribute to the sustainability. To assure that workers do segregate materials, the access to the trash bin should be easy.

O&M

The design can really influence operation and maintenance. As mentioned before material choice has an impact but also careful design can make the building to be easy in use. If it will be foreseen by the architect that there will be needed additional space for storage or access to shafts for instance, he/she can implement it into design and in this way, decrease O&M costs. Analysis of use phase before even constructing the building can detect problems and prevent them.