Tag Archives: sustainable

Passivhaus explained

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Increasing the energy efficiency of buildings is a key concern for a sustainable architect. In this blog post, we look at the basic principles of the Passivhaus (or Passive House) standard: a sustainable construction concept that is the fastest growing energy performance standard in the world. Developed in the early 1990s in Germany, the standard can be applied to any type of building – residential, commercial, public and industrial – in any part of the world. 30,000 buildings now have the standard worldwide, with more and more non-residential buildings such as administrative buildings and schools being built to Passivhaus standards. Passivhaus standard components are also being applied to retrofit projects.

Passive house

So, what exactly is a passive house?

Not to be confused with solar architecture, although it shares some common principles, the key concern for an architect designing a passive house is to reduce dramatically the need for space heating/cooling and primary energy consumption, while at the same time creating good, healthy indoor air quality.

A well-designed and constructed passive house can allow for energy savings of up to 90% when compared to typical building stock in Europe, and over 75% when compared with the average new build designed for low energy consumption. This means that passive house owners and tenants tend not to worry about rising energy prices – passive houses require less than 15 kWh/(m2/yr) for heating and cooling, compared to an average of 150 kWh/(m2/yr) for the space heating demands of a typical house built since 2000.

A passive house uses energy sources from within the building, such as body heat, heat from the sun or light bulbs, or heat from indoor appliances to create a comfortable, healthy living environment. A mechanical heat recovery ventilation system allows fresh air to enter the building without letting heat out, and allows heat contained in exhaust air to be reused. This highly efficient heat recovery system means that fresh air is supplied without draughts and guarantees low radon levels and improved health.

In order to ensure that the ventilation system is effective, a passive house must be properly insulated and airtight, allowing for minimal air leakages in and out of the building through thermal bridges such as the walls. This means that heat can be kept out during the summer and in during the winter. Windows are triple paned glazing and the whole building is oriented so that shade is received in the summer and low angle sunlight in the winter.

It is an exciting time to be working with the Passivhaus sustainable construction standard. Even though ventilation systems require an extra investment, passive house owners/users can save a considerable amount of money over the long-term in energy savings, with many projects showing how applying the standard can be surprisingly affordable as a new build. A Resolution of the European Parliament in 2008 called for implementation of the standard in all member states of the European Union by 2021. With 2020 as a deadline for all new buildings to be nearly ‘zero energy’, the Passivhaus standard provides architects across Europe with a robust, holistic set of guidelines for achieving this goal.

 

Sustainable architecture principles: environment, energy, efficiency

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Buildings account for about half of the UK’s carbon dioxide (CO2) emissions. Globally, architecture was responsible for 40-50% of waste deposits in landfills at the turn of the new millennium, and 20-30% of greenhouse gas emissions.

The environmental integrity of a building (i.e. how it is designed and operated) is now a key consideration in the design of new buildings and the renovation of existing ones. More and more architects and designers are realising that good design improves quality of life and minimises harmful impacts on our health. Clients are also seeing the benefits of more environmentally responsible buildings through future-proofing, reduced operating costs, and comfort and health benefits. As a result, we are seeing more ‘sustainable architecture’ projects, which seek to minimise the negative environmental impact of buildings by efficiency and moderation in the use of materials, energy and development space.

Sustainable architects

So, what are the three main characteristics of a sustainable architecture project?

Environmentally-friendly building materials
A sustainable architect typically chooses to use environmentally-friendly building materials. The most desirable materials are those that are recycled or renewable, as well as those that require the least energy to manufacture. There is often a focus on using locally-obtained woods and stone, reducing the distance that materials travel before being used in the construction process and supporting local trades. There is a preference for wood that is harvested responsibly from certified forests and all other materials are non-synthetic and non-toxic. Recycling is at the heart of a sustainable architect’s design. Although recycled building materials were difficult to source in the early 1990s, there is now an active trade in recycled architectural salvage, particularly by specialist companies providing materials from demolition sites.

Energy and resource efficiency
Sustainable architecture is underpinned by a philosophy that advocates sustainable energy sources. Where feasible, steps are taken to design for energy efficiency, including the use of renewable energy sources such as wind, geothermal and solar. A sustainable architect recognises that the energy efficiency of buildings can be increased in a variety of ways. A building can be oriented to take full advantage of seasonal changes in the sun’s position, and energy-efficient lighting and appliances can be installed. Energy conservation is also key: buildings can be ‘weatherised’ for maximum protection against the loss of warm or cool air, and appropriate insulating materials and window glazing can be installed to reduce heat loss in ways that do not cause indoor humidity.

Efficient use of space
The sustainable architect recognises the importance of indoor environmental quality for affecting how an individual feels in a space and focuses on features such as a healthy indoor environment with adequate ventilation, temperature control, and the use of materials that do not emit toxic gases. The incorporation of earth shelters, roof gardens, and extensive planting throughout and around buildings is also encouraged. In the UK, a study by CABE (Commission for Architecture and the Built Environment, now Design Council Cabe) of five new academic buildings and campuses found that more than 70% of staff and students believed that the facilities and functions of the buildings they work in improved the way they felt and behaved.

Buildings built to the Passivhaus standard are a great example of these sustainable architecture and design principles in practice. We’ll be writing more about Passivhaus in our next post.