In the coming years, the EU Directive on the Energy Performance of Buildings (EPBD) will be implemented into Swedish law. The Directive does not merely introduce stricter energy requirements for new constructions; it also represents a shift in how the energy performance of existing buildings is to be assessed, compared and developed over time. The emphasis moves away from isolated measures and measured operational outcomes towards more function-based requirements, normalised calculation methods and a clearer focus on long-term planning.

In this context, the Swedish National Board of Housing, Building and Planning (Boverket) has circulated for consultation a new regulatory package that will gradually replace parts of the current Building Regulations (BBR) and the regulations on energy calculations (BEN). Boverket’s proposal for regulations on energy conservation.

At the core of the proposals are new, more modular provisions on energy efficiency, including a revised method for calculating energy performance. The modular structure is designed to allow for stepwise tightening of requirements, clearer application in cases of alteration and refurbishment, and a formalised adjustment mechanism whereby requirement levels are to be assessed against the building’s actual technical and economic conditions. It is important to state clearly that the new provisions will not in themselves impose mandatory energy renovations on property owners. What lies further ahead, however, are national obligations on Member States to stimulate energy renovation through various forms of support and incentives directed at owners of the least energy-efficient building stocks.

Boverket proposes that the new provisions should enter into force progressively from 2026 onwards, with different dates depending on regulatory area and application. For new buildings, the ambition is early implementation, whereas alteration and refurbishment measures may in certain cases be subject to transitional provisions. At the same time, it is clarified that existing buildings will increasingly be assessed according to a coherent energy logic rather than through isolated measures.

Before examining how the new calculation model affects a typical multi-residential building from the 1960s and 1970s, it is important to understand the broader context of the change. This is not simply a matter of introducing a new energy figure or adjusting a calculation rule. It represents a broader shift in how energy performance is used as a regulatory instrument – from verifying achieved values to serving as a tool for planning, prioritisation and long-term development of the building stock.

Against this background, there is a clear need to translate regulatory principles into practical consequences for existing buildings. This Insight article therefore takes as its starting point a typical Swedish multi-residential building from the 1960s–70s and analyses how the new energy performance method alters the assessment of the building, the choice of measures, and the requirements for documentation and planning. The perspective is methodological rather than normative. The focus lies on how to build a coherent and long-term decision-making framework as regulation moves from measure-driven to function- and planning-driven governance.

Starting Point: A Typical 1960s–70s Multi-Residential Building

Our reference building is a multi-residential property constructed around 1970, with district heating as the primary heat source, mechanical extract ventilation (F) or early heat-recovery ventilation (FTX) in some parts, and a thermal envelope broadly reflecting the standards of the period. The building is well maintained but has not undergone comprehensive energy renovation. Windows may have been replaced in stages, and the attic may have received additional insulation, but façades and structural systems remain largely unchanged.

Under the current regulatory framework, such a building often occupies an intermediate position: not technically deficient, yet far from meeting present-day new-built standards. At the same time, this building type represents a very large share of the Swedish housing stock, making its treatment central to the implementation of the EPBD.

How Is the Building Assessed Under the Current Method?

Under the present BBR and BEN logic, a building’s energy performance is primarily assessed through a composite indicator based on delivered energy per square meter per year, adjusted using weighting factors. The result is influenced not only by the building’s technical characteristics but also by actual operation, control strategies and occupant behaviour, particularly regarding indoor temperatures and domestic hot water use.

In practice, this means that two fundamentally similar buildings may receive different energy performance results depending more on how they are operated than on how they are constructed. For a 1960s–70s building, relatively limited measures – such as operational optimisation, system balancing or supplementary photovoltaic installations – may yield an apparently acceptable energy figure, even though the building’s underlying energy demand remains largely unchanged.

The New Method: A Different Perspective

Under Boverket’s proposed provisions, this perspective changes fundamentally. Energy performance is to reflect more clearly the intrinsic energy demand of the building and its technical systems, calculated under standardised and normalised assumptions (so-called category-typical values). Indoor temperatures, domestic hot water use and operational conditions are more explicitly fixed within the method, reducing the impact of individual usage patterns.

For our reference building, the focus thus shifts from how little energy happens to be delivered in practice to how much energy the building actually requires to function as housing under specified input conditions. Electricity is not considered solely in terms of kilowatt-hours but also in relation to peak power demand. On-site solar electricity is not treated as an isolated addition capable of compensating for high base consumption, but rather in relation to the building’s overall energy balance.

What, Then, Happens to the Building?

Under the new method, a clearer pattern emerges. The building exhibits a relatively high heat demand per square meter compared with newer buildings, ventilation systems with limited heat recovery, and a thermal envelope where further improvements often require extensive interventions. These characteristics become more difficult to obscure through operational assumptions or supplementary technical installations.

This does not mean, however, that the building is automatically deemed inadequate or that extensive measures are required. Rather, it becomes clearer which aspects of energy performance are structural and which can reasonably be influenced through proportionate interventions.

Unprofitable Measures and the Adjustment Mechanism

In this context, Boverket’s ambition to minimise the risk of economically unjustified measures becomes concrete. For buildings of this type, certain technically possible interventions – for example very extensive thermal envelope upgrades or full system replacements requiring major alterations to functioning installations and living environments – may be difficult to justify from a long-term economic perspective.

The new regulatory model is not designed to force such measures automatically. Instead, it introduces a clearer adjustment mechanism, whereby requirement levels are to be assessed against the building’s technical, economic and functional conditions. Crucially, this assessment cannot take place implicitly. The reasoning must be explicit, documented and traceable over time – precisely the role envisaged for an energy renovation plan.

Planning Over Time as a Governing Principle

For the 1960s–70s building, this represents a clear shift in approach. Instead of focusing on which measures must be implemented immediately, the central question becomes how the building’s energy performance can be improved stepwise and rationally over time, in alignment with natural maintenance cycles and technological development.

Here, the new calculation method connects naturally with structured energy renovation planning. For older multi-residential buildings, this may mean postponing certain measures, combining them with future refurbishments, or replacing them with alternative solutions that yield a better overall effect, without locking the property into costly or short-term decisions.

Implications for Property Owners

For owners and managers of multi-residential buildings from the post-war expansion period, the new regulatory model does not necessarily imply stricter requirements, but it does impose clearer expectations regarding analysis, structure and forward planning. It will be less sufficient to demonstrate that the energy performance indicator happens to fall within acceptable limits. It becomes more important to explain why certain measures are implemented, why others are not, and how the building’s energy performance is intended to develop over time.

In return, the risk of being compelled to undertake technically correct but economically questionable measures is reduced – provided that the property owner can present a coherent and well-founded decision-making framework.

Summary

For the large stock of 1960s–70s buildings, the new energy performance method represents a shift from short-term optimisation to long-term understanding. The regulatory framework becomes less measure-driven but more demanding in terms of analysis, documentation and strategic planning. It is in this light that Boverket’s ambition to modernise the regulatory structure while reducing the risk of unprofitable measures should be understood.

For property owners working methodically and with a long-term perspective, this may mean greater freedom of action – but also clearer responsibility for how the building’s development towards improved energy performance is justified and planned.

In short: more reliance on sound judgement throughout.

The revised EPBD directive marks a clear shift in how energy efficiency is approached. For Swedish property owners, the coming years will be less about immediate renovation obligations and more about requirements for planning, transparency and strategic foresight. At the centre are energy data, long-term targets – and new ways of structuring renovation decisions over time.

From individual measures to strategy

EPBD signals a transition from a traditional, measure-based approach towards a more integrated strategy for the long-term development of buildings. Rather than focusing on individual technical interventions, the emphasis is placed on understanding a building’s energy performance as part of an ongoing process. The key question is no longer whether energy efficiency improvements should take place, but how they should be implemented step by step, in what sequence measures should be prioritised, and at which points in time they are most rational to carry out.

The first important milestone is 2026, when EPBD is to be transposed into Swedish law. At this stage, the change is primarily methodological. The energy performance certificate system is further developed, requirements for energy data are tightened, and new planning instruments are introduced. For property owners, this means that energy performance must be described, analysed and followed up more systematically than before, rather than new technical requirements taking immediate effect.

The renovation passport – function before terminology

A central element of EPBD is what the directive refers to as a Building Renovation Passport. In the Swedish debate, there has been some caution around the term itself, as it can easily be perceived as prescriptive or mandatory. In investigations and background material, it has therefore often been described instead as a stepwise renovation plan, a long-term renovation plan, or a building-specific roadmap for energy efficiency. In practice, however, it is the function that matters, not the label.

The renovation passport is intended as a building-specific, long-term planning document showing how energy performance can be improved progressively over time. It starts from the building’s current state, defines a long-term target, and outlines a logical sequence of measures that can be implemented in line with maintenance cycles, refurbishments or system replacements. The ambition is to reduce the risk of short-term decisions that hinder future improvements or create lock-in effects.

From a legal perspective, the renovation passport is fundamentally an owner-held document. EPBD requires Member States to establish a system for such planning tools, but does not impose requirements for central registration or general regulatory oversight. In a Swedish context, it is therefore likely that the renovation passport will remain an internal decision-support document, used voluntarily in dialogue with advisers, financiers or when applying for support schemes, rather than something routinely requested by local or national authorities.

When requirements become binding

The more binding elements of EPBD come later in the timeline. For new construction, requirements for zero-emission buildings are introduced gradually – first for publicly owned buildings from 2028, and subsequently for all new buildings from 2030. This means that energy performance, system choices and on-site energy production must be analysed already at early design stages.

For existing buildings, it is primarily the non-residential stock that is subject to direct minimum energy performance requirements. By 2030 and 2033, the poorest-performing parts of the stock must be upgraded, based on nationally defined threshold values. Here, the energy performance certificate becomes the key instrument for identifying buildings that risk falling within the scope of mandatory measures.

For residential buildings, EPBD focuses more on improving the average performance of the stock at national level than on an equally strict building-by-building obligation. Nevertheless, regulatory steering may still be strengthened through national policy packages, incentives and potential requirements in specific situations.

From plans to practice with BIM Energy

As energy efficiency evolves from a purely technical issue into a strategic portfolio question, new demands are placed on analysis and decision support. The renovation passport assumes that measures can be analysed in relation to one another, that their interdependencies are understood, and that their effects over time can be quantified.

With BIM Energy, energy performance certificate data and building models can be used as a basis for simulating different renovation strategies. In this way, the renovation passport can be operationalised as a dynamic roadmap, where alternative stages are tested, compared and adjusted as conditions change. The focus shifts from isolated measures to coherent strategies at both building and portfolio level.

A new way of working takes shape

EPBD therefore represents not only new regulatory requirements, but also a changed way of working. Energy efficiency becomes a long-term process, where the right measures must be implemented at the right time and in the right order. For property owners who establish a data-driven and structured approach at an early stage, this creates better decision support, reduced risk and greater flexibility when future requirements eventually become binding.

Renovation passports at a glance

A renovation passport is a long-term, building-specific planning document for stepwise energy efficiency improvements. It is not a permit and does not imply any requirement for immediate implementation. The document is owned by the property owner and is intended to function as decision support over time. EPBD requires that a national system for renovation passports is established, but does not mandate central registration or general regulatory oversight.

The revised EU Energy Performance of Buildings Directive (EPBD) does not only change the requirements placed on buildings. It also changes how property owners need to think about maintenance, investments and long-term value creation.

Instead of isolated technical measures, a framework is established in which buildings’ energy performance is to be improved step by step, systematically and in a traceable manner over time.

For property owners, this means that energy issues can no longer be treated separately from financial planning. EPBD becomes part of the property’s decision logic.

2025 – When the direction became clear

During 2025, Sweden was in the final phase of incorporating EPBD into national legislation. The directive had already been adopted at EU level, and the deadline for implementation was set for May 2026.

At the same time, intensive work was underway to adapt the Swedish energy performance certificate system to the directive’s new structure.

The National Board of Housing, Building and Planning (Boverket) presented proposals affecting both methodology and energy performance classification. A key change is the introduction of a new highest energy class, often referred to as A0, linked to zero-emission buildings.

In parallel, analyses were carried out on how minimum energy performance standards (MEPS) could be designed to function within the Swedish building stock and ownership structure.

For property owners, this phase was characterised by uncertainty in the details, but with a clear overall direction. EPBD should already be taken into account in long-term plans – not as a future regulatory problem, but as a structuring factor for how maintenance and investments are prioritised.

2026 – The regulatory framework is in place

By 29 May 2026, EPBD is to be implemented in Swedish law. This makes the directive’s core structure binding: an updated energy performance certificate system, requirements for a national building renovation plan, and a framework for the stepwise improvement of energy performance in existing buildings.

During the second half of 2026, regulations and guidance are expected to begin giving concrete substance to these frameworks.

It will become clearer how energy performance is to be measured, how energy classes are to be used in property management and reporting, and how, over time, they may be linked to policy instruments and requirements.

For property owners, this means that uncertainty at system level decreases, even though future tightening of requirements is not yet fully defined. It now becomes possible to start adjusting maintenance plans and investment strategies based on a more stable regulatory framework.

2027–2028 – When energy performance becomes an economic issue

During 2027 and 2028, there is a clear shift from regulatory structure to practical application.

The focus increasingly lies on identifying buildings with poor energy performance and ensuring that plans exist for how these are to be improved over time.

At this stage, requirements are likely to primarily concern mapping, planning and follow-up rather than immediate mandatory measures.

At the same time, energy performance certificates based on the new methodology gain full impact, and energy classification begins to play a clearer role in credit assessments, valuations and investment decisions.

This creates a new reality for property owners. Maintenance measures carried out without linkage to energy performance risk becoming difficult to justify, both economically and strategically.

Energy performance becomes an integral part of a property’s financial governance.

2030 – The first threshold effect

Around 2030, EPBD is expected to have a clear impact on the market.

At EU level, the objective is that the share of buildings with poor energy performance will have decreased significantly, and national systems for monitoring and governance should by then be fully established.

For property owners, this means that energy classification is no longer merely an information label, but a market attribute with real significance.

Buildings with poor energy performance risk facing increased requirements, whether through reporting obligations, financing conditions or other policy instruments.

Maintenance plans that do not integrate energy considerations appear incomplete at this stage.

2033–2035 – When long-term planning pays off

By the mid-2030s, Member States are expected to demonstrate that renovation rates are aligned with the EU’s long-term energy and climate objectives.

During this period, the mechanisms of EPBD are expected to take on a more binding character.

In Sweden’s case, this may entail stricter requirements for buildings that continue to have poor energy performance, a clearer linkage between major refurbishments and energy improvements, and increased differentiation in financing conditions based on energy performance.

Property owners who have early on integrated energy performance into their long-term plans will then be well positioned.

They face lower regulatory risk, have better decision-support and achieve more robust value development.

EPBD and BIM Energy – from regulation to decision-making

The fundamental shift introduced by EPBD is not that energy requirements are tightened, but how decisions are expected to be made.

The focus moves from individual measures to coordinated strategies over time.

This is where tools for analysing the interaction between maintenance, energy performance and economics become decisive.

BIM Energy is here the ultimate choice!

By combining energy calculations with economic analyses, such as net present value calculations with time-specific investment events, property owners can make decisions that are robust both technically and financially.

EPBD thus becomes not an external requirement, but an integrated part of long-term property governance.

When energy renovation is discussed, the windows almost always end up centre stage. They are visible, they shape the indoor experience, and they influence energy performance as well as the building’s overall character. Yet the choice between installing new high-performance windows and renovating and upgrading the existing ones is rarely straightforward. Many assume that replacement automatically delivers the most effective outcome, but that view has become far more nuanced as research, industry studies and economic analyses have accumulated.

In many Swedish multi-residential buildings, existing windows account for a significant share of heat losses. Older double-glazed units may have U-values around 2.6–3.0 W/m²K, which makes them considerably weaker than today’s triple-glazed windows that often achieve 1.0–1.2. At the same time, both international field studies and Swedish experience show that renovated windows equipped with interior energy glass, secondary panes or low-e panels can reach U-values as low as 1.6–2.0. This means that a substantial share of the potential energy savings can be realised without replacing the entire window assembly. Importantly, much of the improvement stems not only from reduced heat transfer but from lower infiltration. Draughts, leaky frames and poor junctions between window and wall often have a larger impact on heating demand than many expect, and better sealing, adjustment and insulation can deliver unexpectedly strong results.

One of the strongest arguments in favour of renovation rather than replacement is the climate impact. Life-cycle assessments from recent years show that renovating timber windows can reduce the climate footprint by 50–90 per cent compared with full replacement, since much of the embodied energy already resides in the existing materials. When renovation is paired with energy glass or interior heat-reflective panels, the energy performance is often good enough to meet modern requirements, especially in projects where extremely low U-values are not the primary target. As property owners increasingly incorporate climate calculations into their projects, this factor weighs heavily.

There are, however, equally clear arguments for replacement. New windows are justified when technical condition is poor: rot, warping, recurring condensation between panes or functional problems that cannot be corrected. Projects with stringent requirements for sound insulation, safety or fire performance may also require new windows to achieve the correct classification. And when a façade is being refurbished anyway, coordination benefits can be substantial. A new window with a U-value around 1.0 W/m²K also provides the largest direct reduction in energy use, even if the financial payback time is often long when calculated solely on energy savings.

When these two main pathways are compared, a third factor sometimes disappears in the discussion: comfort. Occupants’ experience of draughts, downdraught and radiant cold often matters more than energy use. Renovated windows, particularly when supplemented with secondary panes, can handle this surprisingly well. Reductions in infiltration of thirty to fifty per cent are not uncommon, and the indoor environment becomes markedly more stable. In many projects, property owners report that improvements in comfort are just as significant as the gains in energy performance.

This is where BIM Energy can play an important role. By modelling the building’s existing window performance, airtightness and solar loads, it becomes possible to compare two or more scenarios and immediately see how energy use, peak loads and indoor temperatures are affected. In practice, this means that a renovated window with U ≈ 1.8 and improved airtightness can be tested alongside a new window with U ≈ 1.1 and very high tightness, making the differences in energy use and comfort visible during both cold and hot conditions. The effect of solar shading can also be built directly into the calculation, which is often crucial for summer temperatures in dwellings with large glazed areas.

Since BIM Energy can also assess the economics, profitability and climate impact of energy-saving measures, it provides a decision base that captures both sides of the equation: long-term finances and climate integrity. Many property companies already work this way, and the pattern is clear: renovation and upgrading of existing windows is often the most cost-effective and climate-sustainable option, particularly when the units are in technically sound condition. Full replacement should primarily be reserved for projects where technical demands, façade reconstruction or an ambition to reach very low energy levels outweigh embodied emissions and higher investment costs.

The conclusion is that window decisions should never be made in advance, as a matter of routine. They must be analysed with data and assessed against the building’s performance objectives. This is precisely where BIM Energy functions as a neutral, transparent decision tool: by simulating realistic scenarios, project teams can see differences clearly and justify their choices to both clients and residents. At a time when energy efficiency, climate responsibility and good indoor environments must be achieved simultaneously, such clarity is invaluable

The Plan, New Legislation, Indicators and the Path to Success

When Boverket and the Swedish Energy Agency presented their respective contributions to the National Building Renovation Plan in October 2025, they did something long requested: they drew a unified roadmap for how Sweden can move from slow renovation rates to a determined, coordinated upgrade of the entire building stock. For the first time, two major authorities speak with one voice: the building sector is not only a climate issue, but also a system of investments, health, safety and social sustainability. Boverket provides the framework – the long‑term plan, the legislative needs and the indicators. The Energy Agency provides the route: how renovations can be carried out cost‑effectively and with technical robustness.

Together they outline a map where all arrows point toward the same goals: fossil‑free operation, reduced energy use and a built environment capable of meeting both climate objectives and the energy‑price challenges of the future.

Boverket’s report states that the new Building Renovation Plan replaces previous strategies; it shall be a concrete, monitorable plan with clear pathways to 2030, 2040 and 2050. The Energy Agency adds the practical questions: when, in what sequence and at what cost? The Agency shows how measures should coincide with natural life‑cycle intervals – when façades, roofs or installations need renewal anyway – and how costs can fall dramatically when timing aligns with the building’s actual condition.

The Right Order of Measures Matters

It is no coincidence that the word sequence appears repeatedly in both reports. First the building’s energy demand must be reduced – improved envelope, ventilation with heat recovery. Then the heating system is replaced, ideally with hybrid solutions involving heat

pumps, district heating and sometimes solar thermal. Finally come controls, sensors and optimisation – the digital layer that ensures the energy savings are actually realised.

Getting the order wrong is costly, the Energy Agency stresses. An oversized heat pump in an uninsulated house can become a 30‑year misinvestment. Boverket agrees, adding the societal perspective: optimisation must be sought across the entire life cycle and reflect Swedish conditions – a low fossil share in the energy mix but high winter peak‑load challenges.

Economic, Not Technical, Barriers Dominate

Renovation is often profitable on paper, but calculations fail when incentives are split. The building owner pays for the investment, while the tenant benefits from the savings. The authorities propose green loans, state guarantees, subsidised credit lines and new rental models that allow energy‑efficiency improvements to be reflected in the rent – something that is normally not possible today, since such improvements are not interpreted as quality‑enhancing for the tenant.

The Energy Agency highlights the need for risk‑sharing: the state taking part of the first‑loss risk or guaranteeing long‑term investment. Boverket stresses that support schemes must be long‑term – stability over generosity.

Competence Shortages Across Many Roles

The renovation pace can only increase if there are enough skilled professionals. The shortage affects energy experts, project managers and property managers who can analyse energy systems, initiate change processes and follow up results. The Energy Agency also emphasises the need for digital renovation passports and certification systems.

Energy Renovation as a Process

For the industry, this means renovation becomes a matter of process and data – not only technology. For housing companies, energy renovation is no longer a project but an investment category. It requires portfolio strategy, financing design and competence development. Large actors are expected to lead the way: they can standardise methods and create reference projects that drive down costs. Private companies should also build dedicated energy‑programme resources with competence in technology, finance and communication.

For detached‑house owners the situation is both simpler and more difficult. A homeowner may decide freely but often lacks capital, advisers and time. Boverket notes that Swedish detached houses already have low fossil‑fuel dependence, but the efficiency potential is large. The Energy Agency gives clear guidance: start by reducing energy demand, not by changing technology first. Improve airtightness in the attic, insulate walls, improve

ventilation – before replacing or installing a heat pump. A smaller pump in a more efficient house gives both lower investment cost and more stable operation. Neighbours coordinating their efforts can reduce costs through joint procurement.

One of the clearest messages is the requirement for monitoring. Results must be measured, verified and reported. For property owners, measurement is essentially survival: without data it becomes difficult to prove that investments deliver results. Those who already build routines for energy logs and verification gain a head start once the plan becomes binding.

Neither authority avoids the social‑impact question. If major renovation packages lead to rent increases, the entire reform risks losing legitimacy. For the sector, communication and transparency therefore become strategic issues. Owners must demonstrate how energy renovations improve not only energy performance but also comfort and indoor climate.

And Now…

The short answer to what should be done now is: start planning, even if not all details are finalised. Survey the portfolio, plan financing, build the organisation and plan the monitoring. Boverket has provided the structure; the Energy Agency the sequence. Together the reports show clear alignment. Those who now establish programmes, secure competence and begin monitoring will be years ahead once the requirements are finalised.

The National Building Renovation Plan should not be regarded solely as an EU obligation, but as a tool for modernising the entire building sector and making energy renovation a natural part of property management.

BIM Energy is the software on the market that allows users – in the simplest possible way – to quickly and accurately identify optimal renovation packages, technically, economically and environmentally.

– Johnny Kronvall | Professor Emeritus, Civil Engineering

From kilowatt-hours to Comfort

As the EU’s Renovation Wave gathers pace and Sweden develops its national renovation plan, attention has mainly been focused on energy performance, emission reductions, and financial feasibility. Yet, in many residential projects, both building owners and occupants find that the greatest benefits of renovation go far beyond energy savings. When walls and windows are upgraded, draughts disappear and temperatures even out, the entire indoor experience transforms — becoming quieter, healthier, and more comfortable. In fact, residents in renovated buildings often report higher satisfaction with their indoor climate, even when the measured energy savings are slightly below expectations.

Thermal Comfort – The Most Underestimated Benefit

A cold wall or leaky window can reduce comfort as much as several degrees’ difference in room temperature. When we sit close to cold surfaces, heat radiates from our body toward the wall, making the room feel cooler than it actually is. A better building envelope — with improved insulation, airtightness, and well-insulated windows — reduces this asymmetry between air and surface temperatures. The result is enhanced indoor comfort, fewer draughts, and less need to keep indoor air temperatures high.

The Critical Balance Between Airtightness and Ventilation

When airtightness improves, unintentional leakage decreases. This benefits the energy balance but also requires careful consideration of ventilation. In older buildings with natural ventilation, airtightness improvements can paradoxically worsen indoor air quality unless outdoor-air supply is ensured. Modern mechanical ventilation systems with heat recovery (FTX) can, on the other hand, provide both better air and lower energy losses – reducing CO₂ levels, controlling humidity, and filtering out particles. EU Horizon 2020 projects show that combining improved airtightness with FTX ventilation can cut energy use by up to 30%, while at the same time increasing occupant satisfaction.

Moisture, Sound, and Light – The Forgotten Qualities

Moisture is the most critical factor in building physics. A tighter envelope reduces the risk of moisture convection – humid air leaking through the structure. If this moist air meets a cold surface, condensation may occur, potentially leading to mold or rot. This often happens in attics after additional insulation, if the air barrier in the ceiling structure has not been properly sealed. A thorough analysis of vapor barriers and ventilation strategies is therefore essential. Energy renovation also improves the acoustic environment — almost always for the better. New low-U-value triple-glazed windows reduce traffic noise far more effectively than old double-glazed ones. Daylight is affected too: the choice of glazing determines how much solar gain and daylight enter the room, which is especially important in northern climates.

Health, Well-Being, and Social Effects

The World Health Organization estimates that around 20 % of Europe’s population live in homes affected by inadequate heating or problems with damp, or mold. The link between poor indoor climate and ill health is well-established: cold homes increase the risk of respiratory illness, and damp or mold is associated with asthma. Renovation mitigates these risks – particularly for the elderly and children. Residents in renovated homes report better sleep, less coughing, and greater comfort. For property owners, this translates into fewer complaints, lower tenant turnover, and a stronger market reputation.

The Risk of Overheating in Summer

In recent years, a new challenge has emerged — partly due to climate change: overheating during summer. A well-insulated and airtight building without proper solar shading can quickly become too warm during hot spells. The Swedish National Board of Housing (Boverket) has observed that indoor temperatures in newly renovated buildings often exceed 26 °C for several consecutive days. A holistic approach is needed – combining envelope design, ventilation, solar control, and occupant behavior. Simulation in BIM Energy can predict these effects and help optimize solutions.

Property Economics and Long-Term Added Value

For a property owner, operating costs are only part of the equation. A building perceived as draughty or noisy often suffers from shorter tenancy periods and more complaints.

After a well-executed energy renovation, the property becomes more attractive, maintenance costs decrease, and its value rises. The Swedish Property Federation (Fastighetsägarna Sverige) has shown that improved comfort correlates with higher market value.Renovations also strengthen prospects for environmental certifications such as Miljöbyggnad or BREEAM In-Use.

Conclusion – When Comfort Becomes the Hidden Gain

Reducing energy use in buildings is essential for achieving climate goals. But every energy renovation also carries something more: the opportunity to create healthier, quieter, more comfortable homes. Improvements to the building envelope and technical systems enhance thermal comfort, air quality, and acoustic conditions – boosting well-being and satisfaction. For both building owners and occupants, this is an investment in quality of life – not just in energy metrics. Want to understand the technical and economic effects of different renovation measures? Explore BIM Energy – the tool that lets you simulate all of this in one single interface, quickly and easily.

You can start a free trial directly on the BIM Energy website!

In order for apartment building owners and managers in Sweden to be well prepared for the upcoming requirements of the EU Renovation Directive, it is important to think and act with a long-term perspective now. A wise starting point is to carry out a thorough energy audit of the building to identify which parts are most energy-intensive and which measures will have the greatest impact and be most cost-effective. The BIM Energy software is the obvious tool for this!

Based on this, it is then natural to update the maintenance plan, not only with traditional repairs but also with energy efficiency measures and a realistic budget for implementing them.

In parallel with this, technical systems such as heating, ventilation, lighting and control systems should be critically reviewed, with a focus on replacing or upgrading those that do not meet today’s energy efficiency requirements. The possibilities for local energy production, such as solar cells or heat pumps, should be evaluated, especially since the new Zero Emission requirements will reward a high proportion of renewable energy.

At the same time, it is wise to follow the development of Sweden’s national building renovation plan, which the Swedish National Board of Housing, Building and Planning will present in 2026, as it will specify time frames, target levels and what forms of financial support will be available. Acting in line with these guidelines offers advantages, both by maximising the possibility of subsidies or green loans and by minimising the risk of having to make hasty and expensive adjustments when new rules come into force.

It is also important to keep an eye on changing expectations in the property market. As energy performance becomes a clearer indicator of quality, buildings that have not been made energy efficient will lose value and attractiveness. By starting the work in good time, owners and managers can not only reduce operating costs and increase the value of the property, but also avoid future problems with letting and selling when energy requirements become stricter. In other words, it is not just a matter of complying with future legal requirements – it is also a strategic investment in the long-term profitability and competitiveness of the building.

As more people look to make sustainable choices for both the environment and their wallets, solar energy is becoming increasingly popular. But how do solar panels actually work? Let’s take a closer look at this technology that converts the sun’s energy into electricity and how solar panel systems are structured.

Solar Energy and Solar Power

Before diving into the details of solar panels, let’s clarify an important distinction:

• Solar energy refers to all the energy present in sunlight.
• Solar power is the electricity generated from solar energy.

Two Main Ways to Harness Solar Energy

There are two primary methods for utilizing the sun’s energy:

1. Solar collectors – These are used to heat water for heating and domestic use.
2. Solar panels – These directly convert solar energy into electricity, which is our focus in this article.

How is a Solar Panel System Structured?

A solar panel system consists of multiple panels, each made up of smaller components. Here is a simplified description of the six basic parts of a solar panel:

1. Aluminium frame – The outer frame holds the panel together and protects the internal components from damage. It also makes the panels easier to transport and install.
2. Tempered glass – The glass protects the solar cells from weather and other damage. It allows more light to pass through than regular window glass and often has an anti-reflective coating to minimize light reflection and increase efficiency.
3. Solar cells – The actual solar cells are embedded between two layers of protective lamination material. These cells are often connected in series, and a panel usually contain 60 or 72 cells depending on its size.
4. Back sheet – The back of the panel protects the solar cells. The most common type is opaque, but some models have glass backs that allow light to pass through both sides, which can increase efficiency but also raise costs.
5. Junction box – This is where the panels are connected to form a complete solar panel system.

Monocrystalline vs. Polycrystalline Solar Cells

There are two main types of solar cells: monocrystalline and polycrystalline. Both are made from silicon but have different atomic structures:

• Monocrystalline solar cells: These have a more orderly structure where the atoms are symmetrically arranged in rows, making them more efficient at capturing solar energy. They offer higher efficiency but are also more expensive.
• Polycrystalline solar cells: These have a less organized atomic structure, making them slightly less efficient but more affordable.
  Nowadays, monocrystalline panels are the most commonly sold, as they provide better efficiency and performance.

How Do Solar Panels Work?

When sunlight hits the solar cells, they absorb some of the energy. This causes electrons in the solar cells to move, generating an electric current. This current can then be used as electricity.

Mounting Solar Panels

There are several ways to mount solar panels on a roof, depending on the roof’s slope:

• Tilted systems: On low-slope roofs, panels are mounted on structures, usually at an angle between 10–15 degrees.
• Roof pitch installation: If the roof has a slope greater than 5-6 degrees, the panels are typically installed to follow the roof’s natural inclination.

The Most Common Installations:

• South-facing system: This setup generates the most electricity, especially during the hours when the sun is highest in the sky. However, to prevent the panels from shading each other, more space between rows is required, which demands more roof area.
• East-west system: This setup generates slightly less electricity per panel but a higher total production because more panels can fit in the same area. East-west installations produce energy more evenly throughout the day, which can be advantageous depending on your electricity consumption.
• Facade installations: These produce about 70% of the energy compared to roof installations and have a higher risk of shading and dirt buildup. Facade installations should be avoided if possible.

Other Equipment: The Inverter

Another essential component of a solar panel system is the inverter. Solar panels generate direct current (DC), but most appliances and the power grid use alternating current (AC). The inverter converts the generated DC electricity into AC electricity that can be used in your property or fed into the grid.

Conclusion

Solar panels are an amazing technology that converts the sun’s energy into electricity and contributes to a sustainable future. By understanding how solar panels are built and how installation works, you can optimize the efficiency of your solar panel system. Whether you have a well-angled roof or limited space, there are solutions to fit your needs. Solar energy is not only beneficial for the environment but can also be a long-term financial investment.
With BIM Energy, you can model solar panels to see how they interact with your specific property. The software calculates electricity usage at a minute level, providing a highly accurate picture of actual savings.