Environmental performance of buildings

[edit] Introduction

Environmental performance comprises an combination of factors that can be measured to give an idea of a building’s (or project's or product's or process's) environmental impact during manufacture, use and disposal.

In relation to buildings, the factors usually involved give an indication of the quantity of resource consumed by a building throughout its life and the degree to which its materials can be recycled or re-used.

Typically, factors that can be used to measure environmental performance include:

• Source of materials.
• Use of materials.
• Energy source.
• Energy consumption.
• Water source.
• Water consumption.
• Flexibility, durability and resilience.
• Pollution and waste processing.
• Transport.
• Landscape and ecology.
• Deconstruction and disposal.

Some broader measures include aspects of personal, social and economic welfare although these can confuse the basic issue of the depletion of resources.

Aspirations for the environmental performance of a project might be set out in an environmental plan. In addition, there are a number of third party schemes that can be used to certify levels of environmental performance:

• BREEAM.
• Passivhaus.
• Leadership in Energy and Environmental Design.

Life Cycle Assessment (LCA) is a method for evaluating the environmental load of processes and products during their life cycle from cradle to grave (Ortiz, Castells et al. 2009). It attempts to identify the environmental effects during all stages of the life of a product and produces a figure (or several figures) that represents environmental load (Finch 1994).

[edit] Materials

The materials from which a building is constructed are important in determining its overall environmental performance. Materials such as timber may be considered 'sustainable' as it can be sourced responsibly and regrown relatively easily.

Materials such as brick, metal, concrete and glass may be considered less sustainable as resources are required for their manufacture, releasing more carbon into the atmosphere.

However, it is also important to consider the performance of materials in use: for example, brick may have high embodied energy but this could be balanced by its relative longevity, minimal maintenance throughout its life and good thermal performance. Furthermore, the ability to recycle certain brick types and other building materials when it comes to demolition further increases its performance credentials.

For more information see: Sustainable materials.

[edit] Energy efficiency

How much or how little energy a building uses will depend on its use, design, orientation, location, materials and so on. For example, increasing the amount of insulation in walls and roofs will reduce heating costs and greenhouse gas emissions. Thermal mass can help minimise heat loss, and even out peaks and troughs in temperature during the day.

A thermally efficient building is one that reduces heat losses/gains and so requires minimal heating and cooling.

For more information see: Passive design.

[edit] Daylighting

Maximising daylight will help reduce heating and lighting costs, especially in winter. A building that is designed for the best possible orientation allied with intelligent window design can maximise daylighting to reduce electricity reliance and also capitalise on solar heat gain in winter to lower heating costs.

For more information see: Natural daylight.

[edit] Flexibility

When it comes to change of use or ownership, the ease with which a building can be reconfigured or deconstructed will give it better 'sustainability'. But this will depend on the design, the way materials have been assembled and the materials themselves.

Timber for example can be easily reused – cut, stripped, planed or reshaped – to give it a new life as long as it has not been excessively fastened in place, say by over nailing or with a very strong adhesive. Bricks too can be reused if they were laid with a soft mortar – such as lime mortar – that is more easily separated allowing the brick to be reused. Specifying materials that can participate in the circular economy will give more sustainable buildings.

For more information see: Circular economy and Design for deconstruction.

[edit] Water use

Minimising water usage through greywater recycling and rainwater collection devices, allied with greater efficiency in water usage through plumbing fittings and fixtures, e.g low-flush toilets and water-saving showers, will greatly increase the water efficiency of a building. Minimising water usage also saves consumers money.

For more information see: Water consumption.

[edit] Related articles on Designing Buildings Wiki

• Active thermal mass.
• Computational fluid dynamics.
• Decrement delay.
• Ground energy options.
• Heat loss.
• Heat transfer.
• Insulation.
• k-value.
• Kappa value.
• Natural ventilation.
• Night-time purging.
• Passive building design.
• Stack effect.
• Thermal admittance.
• Thermal labyrinth.
• Trombe wall.
• U-value.
• U-value conventions in practice: Worked examples using BR 443.