Thirty years after its inception, Passivhaus design, which results in high-performing buildings that use hardly any energy, looks set to hit the mainstream.
Imagine a tool that could help you design and manage an entire neighbourhood to use as little energy as possible… even zero fossil fuel energy.
This tool would not only look at the energy consumption of buildings but street lighting, public transport, and electric vehicles too.
It would include the district heating system, the district electricity grid, and short and long-term energy storage, plus the possibility of energy production from renewable sources in the district.
Such a tool exists. It has been developed by the International Passive House Institute, it’s called districtPH and it comes as an Excel spreadsheet.
It allows the user to investigate the long-term consequences of planning decisions using their own performance indicators, such as an increase in the refurbishment rate, changes in the quality of refurbishments, construction or extension of district heating grids and the creation of renewable energy.
It works by categorising each building by type. A realistic assessment of the heating demand, using appropriate indoor temperatures, is made. It then calculates user-related energy consumptions like domestic hot water and household electricity, given any energy source.
Users don’t need installation or specific software skills to use the tool. It can also be passed from the consultant to the client for them to examine.
Questions that can be asked of the spreadsheet include: “What is required to make the district zero carbon?”, “what size should seasonal heat storage be?”, “how much energy can I export from the district” and “what will be the carbon emissions in the future?”, depending on the situation.
The study behind the model combined many different data sources, such as a digital terrain and surface model, data from energy certificates, population registers and accounting data from the local utilities.
One problem identified was that the condition of a building, its refurbishment status, is often unknown by local authorities. The best that can be understood is through the data from the Energy Performance Certificate.
districtPH is part of the Sinfonia Work Package, a Smart Cities project aimed at deploying large-scale, integrated and scalable energy solutions in mid-sized European cities by retrofitting over 100,000 m² of floor area in dwellings, optimising the local electricity grid, and finding the best district heating and cooling techniques.
Online community for “Passivhaus cities”
There’s an online community of cities attempting to create Passivhaus districts that share the experiences of eight demonstration cities and seven “early adopter cities” with knowledge sharing, study visits and smart city events.
They offer peer to peer support to other cities and communities interested in implementing their own district-scale refurbishment strategies towards greater energy efficiency. There are seven British cities in the cluster in all four principalities – almost half in Scotland.
Affordable Zero Energy Buildings
The project runs alongside an Affordable Zero Energy Buildings project – aimed at achieving significant construction and lifecycle cost reductions for new Nearly Zero Energy Buildings.
Managed by the iPHA and the Passive House Institute, it will create a common methodology for cost-effectiveness.
Training is also available for the necessary skills with a network of training centres and a related app that helps you learn tips and tricks to make your homes energy efficient with learning material and quizzes.
A study using life cycle assessment (LCA) of the environmental performance of three AZEBs published last month found that their environmental impacts are somewhat higher in the construction and renovation stages, because of thicker insulation layers, use of triple glazing and possibly solar collectors.
This is well compensated by lower impacts in the use stage thanks to energy saving and renewable energy production.
Affordability is defined as reducing life-cycle costs and increasing the value for the customer.
Given that buildings can last over 80 years, estimating life-cycle costs and impacts involves accepting some uncertainties. There are trade-offs between a more environmentally-friendly design and a more cost-efficient one, for the same level of energy performance.
Three different types of buildings were studied: a single family house in Bulgaria, social housing in Spain with eight storeys and 171 inhabitants, and a primary school in northern Italy.
The study recommends using LCA from the early design phases, when decisions have the largest influence on the environmental performance of the building. This helps to keep the costs as low as possible.
The method used for assessing the designs is easily adoptable by any architect or developer since it is kept as simple and quick as possible: one day for data collection, two days for input and calculations, and one day for interpretation and report per case study.
Higher real estate value
A different study last month showed that nZEBs have higher real estate value and occupancy rates than other comparable buildings because of their lower maintenance costs and improved comfort conditions.
To achieve this, it also recommends developers/architects consider the integrated design factors with a multidisciplinary team as early as possible in the project. They would prioritise comfort and air quality as well as reducing energy costs. Also, to consider the interaction of the building with the district, and to monitor it after occupancy.
Social housing is increasingly adopting Passivhaus. The latest is a development for social rent in Glasgow, Scotland, opened by Shettleston Housing Association.
It contains 19 new homes for older people in a modern five storey Passivhaus tower combined with the sensitive restoration and conversion of a 19th century church.
It includes high levels of thermal insulation, triple glazing and Mechanical Ventilation and Heat Recovery.
Passivhaus is certainly spreading. In the UK, consultants are offering to work with architects and developers to adapt any design, style or size of building to incorporate all the key Passivhaus principles. They offer to manufacture offsite and deliver and erect the Structural Thermal Envelope.
Next International Passive House Conference
The next International Passive House Conference will be held in less than two weeks, for the first time in China – the city of Gaobeidian. It promises to be the biggest ever, with over 300 abstracts submitted.
It will be followed by the UK Passivhaus Conference, which is looking at mainstreaming Passivhaus by 2030 as a solution to the climate emergency.
This will be followed in November by the International Passive House Open Days. Anyone will be able to visit and experience the benefits of their nearest Passive House buildings – residential and non-residential – first-hand. They can take a look at the ventilation system, doors and windows, and ask questions.
If you have a passive house there is still time to register for it to take part.