Phase-Change Mortars, Energy Poverty, and the Women Retrofitting Nordic Homes
It is February in Oslo. The sun, when it appears at all, barely clears the rooftops before the afternoon light begins to fade. In an apartment bathroom, the floor is warm underfoot — not because the radiant heating is running at this moment, but because it ran last night, during the hours when electricity was cheap and the grid was quiet. The heat it generated was not lost. It was absorbed, silently and invisibly, into the floor itself — captured by microscopic capsules of phase-change material embedded in the mortar beneath the tiles, holding their thermal charge like a slow-release battery waiting for morning.
This is not a technology demonstrator. It is a real installation, in a real building, part of SNUG’s demonstration programme in Norway. The self-levelling mortar incorporating phase-change materials — graphite-encapsulated PCMs blended into a carefully formulated floor compound — has been installed, validated, and is being monitored for its energy performance. Early projections suggest it can shift around 18% of a household’s heating energy consumption from peak to off-peak hours, with associated CO2 reductions of up to 7%. In a country where electricity prices have become deeply political and where the winter energy bill lands hardest on those who can least afford it, those are not small numbers.
This post is about that technology, the people who install it, the people who live with it, and why the intersection of energy poverty, Nordic housing, and workforce inclusion is one of the most important — and most under-discussed — dimensions of the green building transition.
What phase-change materials do — and why it matters for Nordic households
Phase-change materials exploit a basic principle of thermodynamics: the energy required to change a substance from solid to liquid — or liquid back to solid — is far greater than the energy required simply to raise its temperature. A kilogram of a well-chosen PCM can store five to fourteen times more energy per degree of temperature change than a kilogram of concrete or water. Embed that material in a floor mortar, and the floor itself becomes a thermal battery.
SNUG’s initial installation uses a blend of two graphite-based PCMs: one that melts at 20°C, capturing heat at typical room temperatures, and one that melts at 34°C, suitable for higher-temperature radiant systems. The mortar was successfully installed in the bathroom of the Norwegian demonstration apartment, and its workability was confirmed by installation workers to be comparable to or better than standard self-levelling compounds — meaning it can be handled using familiar skills and equipment, without specialist equipment or dramatically altered technique.
The next generation of this material takes sustainability further. SNUG is developing formulations that replace the commercial graphite-based PCMs and conventional mortar binders with bio-based alternatives: coconut oil as the PCM carrier, incorporated into a biochar matrix that replaces part of the sand content, and geopolymer or sustainably blended cement as the binder. The goal is a mortar that delivers the same thermal performance at significantly lower embodied energy and cost — and that uses materials with credible, circular supply chains.
For Nordic households, the appeal is concrete and immediate. Energy price volatility has made the ability to shift consumption from peak to off-peak hours genuinely valuable — not just as an environmental choice but as a household financial strategy. Combined with smart controls that can automate the charging cycle, a PCM floor mortar effectively turns a building’s thermal mass into a responsive grid asset. The household uses less energy at expensive times. The grid is less stressed at peak periods. And the floor stays warm through the morning without the heating system running.
~18% projected reduction in peak electricity consumption for heating, when PCM floor mortar is combined with radiant heating and smart controls.
Up to 7% reduction in associated CO2 emissions — with bio-based PCM formulations expected to further reduce the material’s own embodied carbon.
Energy poverty has a gender dimension — and it lives in the home
Energy poverty — the inability to afford adequate warmth, cooling, or power — affects an estimated 50 to 125 million people across the European Union, depending on the definition applied. It is not evenly distributed. It concentrates in older housing stock, in rural areas, in lower-income households, and in the homes of people whose lives leave them less able to navigate complex energy systems or absorb volatile bills.
It also has a pronounced gender dimension that rarely receives the attention it deserves. Women in Europe are more likely than men to live in energy-poor households — because they are more likely to be the sole adult in single-parent families, more likely to be older and living alone, more likely to be in part-time or lower-paid employment, and more likely to spend more time at home, making the quality and cost of their domestic energy environment directly felt in their daily lives. Research across EU member states consistently shows that women bear a disproportionate share of the burden of inadequate heating — in health outcomes, in the daily management of energy costs, and in the psychological weight of living in cold or damp homes.
Yet the energy retrofit programmes designed to address these conditions — the insulation upgrades, the heating system replacements, the smart control installations — are planned, commissioned, and delivered almost entirely by men, for a policy constituency that is largely defined in gender-neutral terms. The woman managing her heating bill on a fixed pension is the beneficiary of policy; she is rarely the subject of it, and almost never the installer delivering it.
This matters beyond symbolism. When the people designing and installing energy retrofit solutions lack direct knowledge of how the households they are serving actually live — who is at home during the day, how heating patterns differ for people with caring responsibilities, what barriers exist to engaging with smart controls or understanding energy tariffs — the solutions they deliver are less well-fitted to the people who need them most. Workforce diversity in retrofit is not just an equity question. It is a quality question.
Workforce diversity in retrofit is not just an equity question. It is a quality question — better-fitted solutions for the households that need them most.
The installation workforce: who is currently doing this work
Self-levelling floor compounds sit at the intersection of several trades: floor laying, screeding, wet trades, and increasingly, smart building installation. The skills required to install a PCM-enhanced self-levelling mortar correctly are not dramatically different from those needed for a standard compound — but they require an understanding of the material’s thermal properties, the implications of coverage thickness and substrate preparation for performance, and the integration with the radiant heating system beneath.
Across Scandinavia and Northern Europe, the workforce performing this kind of installation is drawn primarily from floor laying, tiling, and wet trades — sectors that, like most construction specialisms, are heavily male-dominated. Norway, Sweden, Finland, and Denmark have made more progress than most EU member states on gender equality in many areas of economic life, but construction trades remain persistently resistant to that progress. Female participation in Norwegian construction trades sits well below 10%, and in floor-laying and wet trade specialisms it is lower still.
This is a paradox worth naming directly. The Nordic countries have the most developed welfare states, the most comprehensive gender equality frameworks, and the most generous parental leave and childcare systems in the world. They also have some of the most gender-segregated labour markets in Europe — including in construction, where cultural norms about who does physical, outdoor, or trade work have proved remarkably durable despite the surrounding policy environment. The lesson is that progressive policy frameworks alone do not automatically desegregate construction. Something more targeted is required.
What is more targeted? In practice, it means vocational training systems that actively recruit women into floor trades and wet work, not passively accept whoever applies. It means employers in the retrofit sector who treat gender balance as a hiring criterion rather than a downstream aspiration. It means social housing providers and local authorities — who commission a substantial proportion of the retrofit work where PCM mortars are most relevant — using their procurement leverage to require diverse workforces on site. And it means the projects and technologies generating the demand for this work — including SNUG — making workforce inclusion an explicit part of how they describe and promote their solutions.
The smart home dimension — and new roles for women in building services
SNUG’s PCM floor mortar does not work in isolation. Its full energy-saving potential is unlocked when it is combined with smart controls that can read electricity price signals, weather forecasts, and occupancy patterns to optimise the charging cycle. The building envelope and the building’s digital intelligence work together: the mortar stores the heat; the smart system decides when.
This integration of thermal and digital systems creates a category of work that sits at the boundary of traditional construction trades and the building services and energy management sector — a boundary that is itself shifting rapidly as buildings become more connected. The installer who fits a PCM floor mortar in a retrofit context increasingly needs to understand the smart control system it connects to, just as the building energy manager needs to understand the physical properties of the materials their algorithms are managing.
These hybrid roles — where thermal knowledge, digital literacy, and resident-facing communication all matter — are precisely the kinds of positions where the gender composition of the workforce is still being determined. The building services and energy management sector has higher female participation than the construction trades, though it remains male-dominated overall. As the boundary between the two sectors blurs, there is a genuine opportunity to bring the more inclusive culture of building services into the retrofit and installation space — and to create roles that are explicitly designed around the blend of technical and interpersonal competencies that effective retrofit work requires.
For women who might be deterred from a traditional construction trade by site culture, physical demands, or social dynamics, roles that combine thermal installation, smart system commissioning, and resident engagement may offer a more accessible and more attractive entry point. Designing those roles deliberately — rather than allowing them to default into the existing mould of construction trades — is a choice that retrofit programme managers and employers can make.
Roles that combine thermal installation, smart system commissioning, and resident engagement may offer a more accessible entry point — if we design them deliberately rather than letting them default to the existing mould.
Connecting the technology to the community it serves
There is one more dimension worth naming in a post specifically about Nordic housing and energy poverty: the relationship between the retrofit workforce and the communities it works in.
Retrofit work in social housing, in older apartment blocks, in the homes of elderly residents living alone — this work requires more than technical competence. It requires the ability to enter someone’s home, understand their daily routines and constraints, explain what is being done and why, and leave the household in a better position than it was found — not just thermally, but in terms of their confidence in and understanding of the energy-saving system that has been installed. A PCM floor mortar that is never optimally charged because the resident does not understand the smart control interface is a wasted investment.
This resident-facing dimension of retrofit work is consistently undervalued in how the sector thinks about skills and training. It is treated as a soft add-on rather than a core competency. And yet it is precisely this dimension — the quality of the human interaction between the retrofit worker and the household — that determines whether the energy savings predicted by the technical specification are actually realised in practice.
Research on resident engagement in retrofit programmes shows consistently that trust, communication, and cultural sensitivity between installer and householder significantly affect both satisfaction with the work and subsequent energy behaviour. Diverse retrofit teams — including women, including people from the same communities as the households being served — consistently perform better on these dimensions. The case for inclusion is not separate from the case for technical quality. It is part of it.
Norway demo
SNUG’s PCM mortar installation in Norway has confirmed workability comparable to standard self-levelling compounds. Monitoring of energy consumption is ongoing, with results expected to demonstrate real-world peak-shifting and cost reduction for the demonstration household.
Next generation
Development is underway on a GEO-Biochar-PCM mortar formulation replacing commercial graphite-based PCMs with bio-based alternatives (coconut oil in biochar matrix) and conventional binders with geopolymer, targeting significant reductions in embodied carbon and material cost.
Smart integration
Full energy savings are achieved when PCM mortars are combined with smart control systems that optimise charging cycles based on tariff signals and occupancy. Installer training for this integrated system represents a new and inclusive skills opportunity at the boundary of construction and building services.
Warmth is not a luxury — and neither is inclusion
The household in the Norwegian demonstration apartment has a warmer floor in the morning, a lower electricity bill over the month, and a slightly reduced carbon footprint over the year. These are modest, incremental gains at the level of the individual household — but multiplied across the millions of Nordic homes that could benefit from this technology, and across the European housing stock more broadly, they become something significant.
The same logic applies to workforce inclusion. A single woman trained in PCM floor installation, or in smart retrofit commissioning, or in the resident engagement skills that make retrofit work deliver its promised savings, is a modest and incremental gain at the level of the individual. Multiplied across the training systems, the apprenticeship programmes, the procurement conditions, and the employer hiring practices of a sector undergoing the largest transformation in its history — it becomes something that changes the face of the industry.
SNUG has developed a technology that can make Nordic homes warmer, cheaper to heat, and less carbon intensive. The workforce that installs it should reflect the communities it serves — including the women who bear the heaviest burden of energy poverty, and who have, so far, been largely absent from the rooms where the solutions are being built.
That absence is not inevitable. It is a choice — made, or not made, in training curricula, in hiring practices, in procurement conditions, and in the way that projects like SNUG choose to tell their story. Telling it differently starts here.
Next in this series: Eco-Concrete, Industrial Transition, and the Communities Left Behind — or Brought Along
SNUG is a Horizon Europe project developing circular economy-based sustainable insulation materials and prefab solutions for building envelopes. This blog series explores the intersection of materials innovation and workforce inclusion.
By courtesy of CRES – Centre for Renewable Energy Sources and Saving
