Energy renovation of non-residential buildings in Sweden

Abstract

The recast Energy Performance of Buildings Directive introduces binding Minimum Energy Performance Standards for existing non-residential buildings, requiring Member States to identify and renovate the worst-performing segments of their building stock. This study develops and applies an integrated framework for evaluating energy renovation measures in office buildings, addressing building category selection, model fitting under data uncertainty, and techno-economic assessment of renovation packages.

Two office buildings of similar construction period in Stockholm, both connected to district heating, were selected as case studies. Building energy models were developed and fitted against measured heating energy data, based on the most impactful parameters, followed by a parametric simulation evaluated against the calibration criteria of ASHRAE Guideline 14. Three energy models were retained per building to preserve residual modelling uncertainty. Among the input parameters investigated, ventilation system parameters showed the strongest influence on simulated heating demand.

A systematically selected set of renovation combinations was evaluated through parametric simulation, assessed using energy savings and simple payback time for individual measures and a profitability framework for packages. Ventilation-related measures, specifically AHU replacement and conversion from constant to variable air volume operation, consistently delivered the highest energy savings combined with short payback times across both buildings and all energy models with average return on investment of 27 % and 40 %, respectively. At the package level, the replacement of the air handling unit together with LED lighting formed a high-return renovation package with a cumulative return on investment above 30 %. The further conversion of the ventilation system control from constant air volume to variable air volume increased the energy savings while keeping the package return on investment above 25 %. Adding roof insulation to the package consistently yielded moderate returns, with a cumulative return on investment of approximately 20 %. Window replacement provided a secondary contribution but highly sensitive to the precondition of the existing windows, at substantially higher investment cost. Lighting and pump replacement had marginal impact on total energy use despite relatively low investment.

The ranking of measures remained consistent across the three energy models selected per building, suggesting limited impact on the choice of interventions to modelling uncertainty for the building characteristics studied. The methodology supports structured identification of effective renovation pathways for office buildings sharing similar functional characteristics, providing a pathway to support energy improvement required by Minimum Energy Performance Standards under the recast Energy Performance of Buildings Directive.

Popular Abstract

Energy renovation of non-residential buildings in Sweden

Renovating Sweden's offices: which upgrades are truly worth the money?

New EU rules will soon force the worst-performing offices and other non-residential buildings in Sweden to be renovated. This thesis built a step-by-step method to work out which renovation measures actually save energy and money and found a clear winner.

Europe's recast Energy Performance of Buildings Directive does something it never did before: it sets binding Minimum Energy Performance Standards for existing non-residential buildings and tells each EU country to renovate the worst performers in its stock. The intention is clear, but for an owner facing a long list of possible renovations, one question is surprisingly hard to answer: which renovations should be prioritized?

Answering that is harder than it sounds. Non-residential buildings vary enormously in how they are used, how much heat they generate inside, and how they are run. On top of that, there is a well-known catch: the energy a simulation model predicts and the energy a building actually uses often disagree. This "gap" makes owners distrust the savings any renovation promises.

The aim of this thesis is to tackle the problem for office buildings, chosen as one of the representative slices of the non-residential stock. The study built an integrated method to cover two things: building energy models that stay honest when the input data is uncertain and weighing up the energy and money side of renovation packages.

Two offices of similar age in Stockholm, both heated by district heating, served as real case studies. For each, where documentation was missing, many plausible versions of the building were simulated and "fitted" against the building's actual measured heating data, checked against an international calibration standard. Rather than choosing one "perfect" model, the study deliberately kept three of the versions that all met the acceptable criteria, so that any conclusion had to survive the remaining uncertainty. One factor stood out as having the biggest effect on heating demand: the ventilation system.

The fitted models were used to test renovation measures. new windows, roof insulation, LED lighting, a new circulation pump and ventilation upgrades; judging single measures on energy saved and how fast they paid back, and whole packages on profitability.

Ventilation upgrades came out on top every time: replacing the air handling unit and upgrading the ventilation to adjust airflow to actual demand rather than running continuously at maximum capacity gave the biggest savings and quick payback, with yearly returns on investment of roughly 27% and 40%, respectively. At the package level, replacing the air handling unit together with adding LED lighting formed a high-return renovation package with an annual return above 30%. Adding the smarter ventilation control kept returns above 25%, and adding roof insulation still managed around 20%. New windows saved relatively little and would not pay back within their 30-year lifetime.

The ranking of the best measures stayed the same across all three model versions for both case studies, so owners do not need perfect information about a building to choose the right renovations. The result is a repeatable method for spotting effective renovation paths in offices and meeting the EU's tightening standards.

• author: Compean Becerra, Ana Sofia and Jafar Zadeh Afshari, Sakineh
• supervisor: Ricardo Bernardo; Ilia Iarkov; Ji Onn Tan
• organization: Division of Energy and Building Design
• course: AEBM01 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Energy renovation, Office buildings, Model fitting, Building energy simulation, Energy performance gap, Ventilation retrofit.
• language: English
• id: 9230933
• date added to LUP: 2026-06-04 07:51:49
• date last changed: 2026-06-10 09:29:13