Part 2: The Passivhaus Homes Myth-Busting Guide

27 April 2016 Rory Bergin, Architect, HTA Design

A myth-busting guide to Passivhaus homes

Potton Elsworth Show Home CGI
Can I open the windows? Will the architectural design be compromised? When it comes to building a passive house (also known as a Passivhaus), there are some common myths about this energy-efficient standard — for example, many people think they have to be “box-like” in design.

Architect Rory Bergin from HTA Design LLP dispels these myths about Passivhaus homes below.

How Significant Is Passivhaus in Delivering Sustainable Housing?

Passivhaus is a standard that focuses almost entirely on the energy used by buildings. It has been very successful in demonstrating that livable and comfortable houses can be built using this standard in a variety of European countries and further afield.

It has had a major influence on the direction of policy in many countries, with some even adopting the Passivhaus standard as optional or mandatory in new construction. All of this is positive as it helps to drive the development of new products and skills in the construction industry, to create even more highly energy-efficient buildings.

Does Building a Passivhaus Home Have to Result in Architectural Compromise?

The Passivhaus standard does have an impact on design to some degree — in the same way that almost all energy-efficiency standards have an effect. Simple volumes and shapes tend to work better than complex ones and the design of the building fabric needs to be carefully considered from the outset to ensure that it performs efficiently. The size and orientation of windows are also important to manage solar gains as well as heat losses.

However, none of this means that designing to the standard is difficult, and our project with Potton demonstrates that an architecturally interesting and relatively complex design can meet the standard. The challenge is to merge both the design considerations and energy-efficiency from the outset as highly energy-efficient buildings need to be designed to perform well from the beginning.

A design is not likely to be cost-effective or successful if it needs to be manipulated after creation to be more efficient. At HTA we include designers and energy-efficiency specialists on our staff, so we can ensure that the design is heading in the right direction from the beginning.

We use computer simulation tools to assess the designs at regular intervals to ensure that we are meeting the required standard. It is also vital that the voices of the designer, client and sustainability expert all have equal weight from the beginning of the process so they can trade-off judgements and opinions.

For this project with Potton, we tested three designs, choosing the one we knew would be the most complex to build from an energy-efficiency perspective. This was because it had the most potential to deliver an exciting design — and we didn’t think that the difficulties of achieving the Passivhaus standard were insurmountable.

The design centres around a small internal courtyard which acts as the focal point of the dwelling. This courtyard is surrounded by the staircase, the living room and the kitchen, and has a roof light that brings daylight into the heart of the home. The house features more accommodation on the ground floor than on the first floor — meaning in other buildings, the design can be varied to accommodate a larger number of bedrooms upstairs.  We liked the idea that there could be many different versions of the home that would suit different lifestyles.

Building a Passivhaus Show Home Guide

Our Building a Passivhaus Show Home manual is a complete step-by-step guide, which takes you through the story of building our Passivhaus show home — from the design process, constructing the superstructure, achieving airtightness right through to the finishing touches. Download the guide here.
Building a Passivhaus Download

How Sustainable Will a Completed Passivhaus Home Be?

Sustainability is not just about what kind of home we live in, but also where we live and how we travel. The Potton Passivhaus, if constructed close to services, transport, shops and amenities, can be highly sustainable. This location offers residents the opportunity to live in a home that uses a fraction of the energy that an old home uses, which can use much less energy than a home constructed to current UK Building Regulations standards.
 
However, the resident will need to participate in this effort as a Passivhaus home cannot do everything on its own. Subsequently, it’s important that doors and windows are kept closed in cold weather to allow the system to maintain a good indoor level of comfort.
 
The experience of residents in completed Passivhaus homes is generally positive with regards to how comfortable they are to live in. A secondary benefit of such a high-performing building fabric is that they are quiet and keep out noise.

Is It True That You Cannot Open the Windows in a Passivhaus?

Image_Show Home_Elsworth_14
This is a myth. The energy efficiency of the house in the coldest part of the winter relies on closed windows — but that doesn’t mean that you cannot open them if you wish.
 
The house will simply get cold, and it will take a while to warm up as the heating system is small. This is because the building is designed to require very little heating, so it makes no sense to install a standard heating system. In the long term, this helps save money, as there is no boiler or radiators to maintain or replace.

Can I Add Renewable Energy Systems?

 
Yes, you can. While we have not added renewables to the showhome, there is plenty of roof space to accommodate solar thermal or photovoltaic (PV) systems. If you have a family with young children or teenagers, then solar thermal may offer the greatest savings as it can provide over half your annual hot water requirement.
 
Adding PV panels also helps to reduce National Grid energy consumption. Grid energy is not “clean” energy, as we still use a lot of coal and gas in the UK. PV panels can help reduce the energy used in a Passivhaus to nearly zero over a year — or even to generate a small income (via the Feed-in Tariffs) if there are sufficient PV cells and the energy use is well-managed by the occupier.

Read Part 3: The Details Behind Passive House (Passivhaus) Construction

Potton Elsworth Passivhaus Show House

The Elsworth is open to the public

We have five self-build homes for you to browse, but the Elsworth is the UK's first permanent show home built to Passivhaus standard, created using our Kingspan TEK Building System.

Come and experience the Elsworth show house for yourself.

Potton

Potton Head Office

Eltisley Road

Great Gransden

Sandy

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441767 676400

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