Published in 4/2021 - Housing


On the Drawing Board: Four Perspectives on Sustainable Housing Construction

Antti Lehto

 Diana block in Sompasaari, Helsinki, combines a large number of different housing typologies. Photo: Tuomas Uusheimo

Climate change can already be seen on the desks of all architects. Antti Lehto, who was recently appointed as Assistant Professor in Housing Design at Aalto University, looks into opportunities of architects to affect the sustainability of housing projects.

In the series “On the Drawing Board”, we ask architects to share their thoughts related to ongoing projects. 

There is a dichotomy in the prospects of urban housing of the future. Along with the climate change, the construction sector will – and so will the entire society – change, which also makes it possible to reform housing construction and housing architecture. Some of the residential housing blocks are already designed carefully and sustainably, using low-carbon materials. On the other hand, the heated and investor-driven market has narrowed down the designers’ opportunities to create good living environments. 

In my work as a designing architect at Inaro Architects, I have had a chance to develop various research-based solutions for the future. In this article, I will bring up four themes dealing with the housing construction of the future: a large variety of dwelling types, low-carbon circular economy, flexibility, as well as new processes and actors.

A Large Variety of Dwelling Types

Parallels can be drawn between a large variety of dwelling types and biodiversity in ecosystems. A large variety of species improves the ability of an ecosystem to adapt to environmental changes. If a structure is versatile, people’s wishes relating to housing that change during the course of decades and centuries will not make the structure entirely useless, and people will be able to move house in their changing situations in life without having to move very far. The adaptability of homes further improves the ability of people to adjust. 

We designed a large number of housing typologies in the Diana block in Sompasaari, Helsinki. The local detailed plan had defined non-subsidised owner-occupied housing, Hitas rental housing and housing for special groups for the plots. 

For designers, it is difficult to develop different dwelling types, as they know very little about the future residents. Even in the Diana block project, the only way to learn about the wishes of the future residents – in addition to the available research data – was to receive information from the clients’ sales organisations and rely on intuition. In addition to the resident profiles, the typological variations are also based on the location of the homes in the block. This way, the project of one developer is visually split into smaller parts, i.e. identifiable buildings. The cityscape becomes rich by using simple and clear methods. In the Diana block project, the relationship between the designers and the developer has been exceptionally practical and spontaneous. At its best, this kind of openness can lead to the development of the design process. For instance, feedback has been collected from those living in the housing of the Finnish Youth Housing Association (NAL) after the completion of the building. With the help of the feedback, the intention is to improve the design solutions in the future sites of NAL. 

For designers, it is difficult to develop different dwelling types, as they know very little about the future residents.

Corner apartment for Finnish Youth Housing Association, Diana block, Helsinki. Photo: Tuomas Uusheimo
Yard of Diana block. Photo: Tuomas Uusheimo
Basic floor, Diana block.

Low-carbon Housing and a Circular Economy

The aim of a circular economy is to make the life cycle of a product longer and circulate materials in such a way that they maintain their value. Amongst the first practical applications of the principle in housing construction is the Jätkäsaari circular economy block in Helsinki. Our company has designed rental housing for young adults in the block, commissioned by NAL Apartments. In the project coordinated by the Yrjö and Hanna Foundation, a report on circular economy in wood construction will also be drawn up in collaboration with ARK-house architects. Even though the project is still in the sketching phase, the circular economy strategies and challenges have begun to take shape. 

In the Jätkäsaari circular economy block, the solutions are divided into various subareas of the building, adapting the famous shearing layers (i.e., stuff, space plan, services, skin, structure, site) by Stewart Brand: some of the structures circulate at a quicker pace than the others. We have summarised the design strategies dealing with circular economy in construction and made it into a table. On one of the axes of the table, there are R-imperatives – selected from the literature – for the processes dealing with the preservation of the value of the material: refuse, reduce, reuse, renew, recycle. The table facilitates the considering of various solutions. For instance, a loadbearing structure contains the largest amount of natural resources, and consequently, the primary solution in the circular economy block project is to use prefabricated box units built of cross-laminated timber (CLT). A cost estimate will reveal the destiny of the chosen path. 

Applying the strategy table to our design work has revealed that the choices made in one sector of a building can restrict or exclude the use of parallel strategies. When, for instance, a material which is as monomaterial as possible and which returns to the biological cycle is selected to be used in the frame of a residential housing block, the current construction methods and cost effects guide to execute construction in which prefabricated box units built of CLT are used. The construction using prefabricated box units sets limits for adaptability: for instance, taller ceiling heights and clear spans that facilitate various uses are excluded and the location of building services technology is more restricted. Also, compromises cannot be avoided. For instance, any treatment of wood should be avoided in order to recover the wood – adhering to the cascading principle – and provide it with another use before it is burned. However, the unglued timber elements that are joined with screws are, so far, too expensive to be used extensively.

The choices made in one sector of a building can restrict or exclude the use of parallel circular economy strategies.

In circular economy projects that are carried out abroad, the aesthetics of reused building components is emphasised. This will be also studied in Jätkäsaari, especially in the part of the facade and the yard. The use of old building components – such as bricks, windows or precast concrete elements – is problematic due to the lack of a value chain and difficulty in gaining an official approval for the products. International research projects, such as the ReCreate project coordinated by Tampere University, are currently delving into these questions. Before an extensive reuse of old structures is possible, their value is, above all, in symbolism: they communicate the turning point. As Panu Savolainen writes in a new compilation Kiertotalous rakennetussa ympäristössä(2021), it would be more important – in place of symbolism – to design new buildings in a way that the natural resources that they contain would be reusable. 

A circular economy changes the designer’s mindset. You have to admit that buildings do not last for ever, no matter how carefully you would design and execute them. The life cycle of a building and the end of its life cycle, i.e. demolition, are increasingly often present in the work of the architect. In the most radical cases, the circulation capacity of recovered materials and structures, or available old construction components, provide starting points for spatial design and aesthetics, and not vice versa. In place of a “completed”, static object, the building appears as an energy and material flow that is piled up, transformed and demolished through societal motivators for change. However, it is comforting that symbolic meanings do not disappear. For instance, according to aesthetics researcher Sanna Lehtinen, sustainable aesthetics is linked to the concepts of care and fostering. They aptly complement the economic discourse dealing with a circular economy. A residential building cannot only be a material storage that protects its resident against the forces of nature, but it must become attached to the resident’s life in a meaningful way. 

Flexibility and Resident Orientation

The adaptability of a building frame and dwelling layouts has been studied – and it has been the objective of designers – for decades, but the list of completed projects is short, particularly in Finland. According to recent Finnish studies, the spaciousness of rooms, the storey heights that make different uses possible and technical reservations have not produced direct benefit for developers, which is why these solutions have not remained in use.

However, adaptability and multifunctionality are receiving support from two directions. The Covid-19 pandemic has concretised the benefits of flexibility. The increase in remote working and time spent at home has already been reflected in the housing market. On the other hand, it can be assumed that the adaptability of a building makes its life cycle longer, and this way, smaller amounts of virgin raw materials and energy that is required for their production are needed than before. 

Our Kotilo concept was approved to be part of the City of Helsinki’s Re-thinking Urban Housing programme in 2021. The programme has already been active for more than ten years. In the programme, developers are encouraged by the City of Helsinki’s experts to develop and execute new kind of housing solutions. 

With the help of our concept, we are able to design exceptionally adaptable homes, thanks to a lift which is located separately from a staircase and which opens directly to the homes. From the staircase, there is an access to the homes via two small “front yards”. This design has drawn inspiration from logics dealing with flexibility and their combinations, named by housing researcher Jyrki Tarpio. An open space logic provides a starting point for many variations, such as an implementation of a hallway and rooms logic and a logic of route variation, around the same staircase. A dwelling is completed for the first resident. The material and window joints, the circuits of floor heating, as well as the reservations for electricity and ventilation are designed in a way that – except for the bathroom – it is possible to make changes to the layout of the rooms with a reasonable amount of renovation. The dwelling layouts can be tailored to current needs, such as remote working or cross-household parenting, as well as to fashion trends that will be popular after decades or centuries – whatever they will be. 

. Kotilo concept allows for exceptionally adaptable homes. A lift is located separately from a staircase and the material and window joints and technical installations are designed in a way that – except for the bathroom – it is possible to make changes to the layout of the rooms with a reasonable amount of renovation.
A. Family with two children moves in, one of the parents works remotely. The rooms have neutral dimensions so their functions can be easily changed. The family uses home delivery services and builds a delivery entrance for the elevator. B. The children don’t want to share the room anymore, so the workstation is relocated in the hall and gets sliding doors. Kitchen and living room become one open space. C. The oldest child moves away, and parents want a proper home office. Located next to the elevator, it welcomes customers without mixing work with private life.

New Construction Management Processes 

According to estimates, new actors and execution methods play a significant role in a systemic change towards more sustainable construction activities. In this light, it is strange that there are very few construction companies that carry out unprejudiced work with a new kind of value base. As a counterreaction to the unambitious atmosphere in the construction sector, we founded – together with architect Aleksi Niemeläinen and three other partners – Woodberg, in order to develop dwellings using solid wood.

One of our completed projects is Prikitie semi-detached houses in Jollas, Helsinki. The architecture has looked for inspiration in the design principles of the wooden housing district of Käpylä in Helsinki. The ecological performance, functionality and spatial quality have been considered in relation to the cost level and aesthetic sustainability of the solutions. The semi-detached houses boast a monomaterial, solid wood structure and natural ventilation. The living areas have been located on the top floor. The kitchen and the dining area open the main floor up towards the west and the residents can enjoy the open views and the evening sun, which shines from the opposite direction. 

It is strange that there are very few construction companies that carry out unprejudiced work with a new kind of value base.

Prikitie semi-detached houses in Jollas, Helsinki, boast a monomaterial, solid wood structure and natural ventilation. Photo: Martin Sommerschield
The living area is located on the top floor. Photo: Martin Sommerschield
As. Oy Prikitie, ground floor and 1st floor.

The semi-detached houses are heated by geothermal energy. A life cycle assessment – in accordance with the method of the Ministry of the Environment – was carried out. In the life cycle assessment, the site was compared to hypothetical versions. The carbon footprint of the selected design was 53% smaller than that of a concrete-frame building that utilises district heating. As regards the construction materials, a timber structure stores more carbon than what is released in the manufacture of all materials for the building.

When acting as a developer, the construction process and its parties become familiar in a new way. Even though Woodberg does not carry out actual joint building ventures, residents have the freedom to modify designs within the given framework and schedule. We have learned to know the residents, who give us direct feedback on the functionality of the design solutions. In addition, we understand the work preceding the actual design work and construction, as well as the related uncertainties, in a new way. We must be able to tie up the plot and financing, or else there will be no project. The counterweight to the challenges is power. Expanding the architect’s job description opens up opportunities to influence and promote more sustainable construction. ↙

Architect SAFA, founding partner of architecture office INARO and development
company Woodberg, Assistant Professor in Housing Design at Aalto University. 

Diana block: Antti Lehto, Emilia Ellilä, Kristiina Östman
Kotilo: Antti Lehto, Emilia Ellilä
Circular economy block report: Miia Suomela, Antti Lehto, Hanna Mattila 
Woodberg, Prikitie 12: Antti Lehto, Aleksi Niemeläinen, Tuomas Voutilainen


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