What is the difference between Passivhaus and BREEAM?

 

At a time when energy prices are rising, it is helpful to know about options in the home for reducing energy consumption. From an architectural and design point of view, this equates to much more than having a shorter shower or reducing the time the heating is turned on. Today, there are several ways to deliver a high standard in energy-efficient construction, using well-developed design principles and sustainability assessment methods. We work with two approaches in particular – Passive House and BREEAM (Building Research Establishment Environmental Assessment Method).

RISE Design Studio Passive House London

Passive House – Energy savings of up to 90%

In recent years, there has been growing awareness of the benefits of a Passive House (or Passivhaus). This is a construction concept that dramatically reduces the need for space heating/cooling and primary energy consumption, while at the same time creating good, healthy indoor air quality. In Europe, a Passive House generally uses as little as 10% of the energy used by a typical building, or 25% when compared with the average new build designed for low energy consumption.

A Passive House relies on energy sources from inside the building, such as body heat, light bulbs, heat from the sun, or heat from indoor appliances to create a comfortable and healthy living environment. A mechanical heat recovery ventilation system is used to enable fresh air to enter the building without letting heat out, and allows heat contained in exhaust air to be reused.

For a building to achieve the Passive House standard, there is strong focus on energy conservation, particularly via insulation, air tightness and optimal glazing.  It is quite a simple approach and checking the design and build against the standard is straightforward.

BREEAM – thinking about carbon emissions

Although more complex to apply in practice, the BREEAM standard is concerned with more than energy conservation. The standard takes into account carbon emissions as well as energy consumption, and is more holistic than the Passive House approach. BREEAM considers the environment/infrastructure surrounding the house – good management, water consumption, biodiversity, transport, pollution, waste management, etc.

This broad-reaching approach allows careful master planning of projects, infrastructure and buildings, which is increasingly important in areas where pressure for housing development is high. BREEAM ratings focus particularly on the reduction of carbon emissions, low impact design, biodiversity protection and climate change adaptation, allowing the client or other stakeholders to compare building performance. To date, an ‘Outstanding’ BREEAM rating has been awarded to less than 1% of new non-domestic buildings in the UK and serves to inspire developers and others to improve, innovate and make effective use of resources.

Sustainability assessment at RISE Design Studio

We regularly work with both the Passive House and BREEAM standards, on both new build and retrofit projects. Our recent work that follows Passive House principles of sustainable design has incorporated the use of air source heat pumps, solar panels, airtightness, mechanical ventilation with heat recovery, and additional insulation.

The focus on sustainable value and efficiency makes Passive House and BREEAM certified projects a worthwhile investment, not least for creating a healthy home or work environment with reduced operational costs, and contributing to sustainability both within and outside the home.

Rammed earth walls: natural and sustainable living

 

‘Rammed earth’ is a technique for constructing foundations, floors and walls from natural raw materials such as earth, chalk, lime or gravel. With the lowest enviromental impact of all building techniques currently used in the commercial construction industry, rammed earth is receiving growing attention and becoming more and more popular with architects, builders and clients alike. In this short post, we tell you a little more about the technique.

Rammed earth walls RISE Design Studio architect west london

Mixing it up

Rammed earth walls are made by ‘ramming’ a mixture of materials into place between flat, temporary panels called ‘formwork’. The panels are normally made of wood or plywood and they are clamped around the earth to make sure it doesn’t bulge when compressed. The materials rammed into the formwork generally include gravel, sand, silt and a small amount of clay.  An additive like lime, cement of asphalt is often added to make it extra strong.

The mixture is compressed inside the formwork by a mechanical ram and compacted to approximately 50% of its original height. The compression takes place in stages, usually in depths of 10cm to 25cm, and this is repeated until the top of the formwork is reached. This is the part of the process that results in the beautiful layers sometimes seen in rammed earth walls.

After the wall has been completed, the formwork is removed and a surface texture can be applied, e.g. by wire brushing or carving. The wall is normally too hard to work on after about one hour. As the walls dry and harden (ideally in warm weather), the compression strength of the rammed earth increases to a maximum of 4.3MPa (620 psi). This is less than concrete but sufficiently strong for domestic buildings.

Environmentally-friendly

Cured rammed earth has a high thermal mass. This means that it absorbs heat during the day and releases it at night, which reduces heating and cooling costs. Environmental impacts are also kept low if the amount of processing of rammed earth materials is kept to a minimum (i.e. artificial additives) and material is sourced locally where possible. Most of the energy used in the construction of rammed earth is in quarrying the raw material and transporting it to the site.

Healthy home

The composition of rammed earth allows it to absorb and release humidity from the inside of a building. This improves air quality, particularly for people who suffer from asthma. Rammed earth is also inorganic, which means that it won’t decay and does not support the growth of mould.

Back to our roots

More than 30% of the world’s population uses earth as a building material, hence this technique is not new. Properly constructed rammed earth can also last for thousands of years, demonstrated by the many ancient structures built using this technique which are still standing around the world.

It has received growing attention in recent years as the construction industry and its customers have a growing sense of the need for environmentally friendly and sustainable building practices. Not only does the technique offer opportunities for carbon-neutral building projects, the technique can be employed in a wide range of climatic conditions and for developing housing that would otherwise be constrained due to expensive construction techniques.

It is a technique that we have been exploring at RISE Design Studio, particularly in our drive to use local, sustainably-sourced building materials.