The energy performance of heritage buildings is attracting growing interest in research and practice. Accordingly, as shown by our literature review, increasing numbers of articles on energy-efficiency measures for heritage buildings are being published in peer-reviewed journals. However, there is no overview of how energy efficiency and heritage conservation have been approached in the studies. To address this gap we categorized and assessed the identified studies in terms of two key elements of such investigations: energy analysis and analysis of cultural heritage values. Most of the studies evaluate and propose measures to reduce the operational energy use of single heritage buildings, and fewer have applied a broader system perspective. Moreover, the underlying notion of the buildings’ cultural heritage values seems to have been derived mainly from international conventions and agreements, while potentially significant architectural, cultural and historical factors have been rarely discussed. Our findings highlight that, when considering energy improvements, cultural heritage values should be more explicitly articulated and analysed in relation to established conservation principles or methodologies. Besides further scientific study, this point to the need of designing best-practice approaches that allow transparency and knowledge sharing about the complex relationships between energy efficiency and heritage conservation of buildings.

The town of Kiruna, founded in 1900 in the northernmost part of Sweden, is nowadays in the middle of an impressive urban transformation: due to the impacts of mining activities a large part of the city center has to be moved or rebuilt. Among the buildings to be moved and kept in use are some of the so-called ‘Bläckhorn’ timber houses, designed by Gustaf Wickman in the early 20th century as residential units for the workers of the mining company LKAB and part of the original core of Kiruna. This has raised several questions on the sustainability of renovating historic buildings in a sub-arctic climate. In order to explore the challenge of increasing the energy efficiency of the Bläckhorn houses, data on their constructional and historical features as well as their thermal and energy performance have been collected. The paper addresses the following issues. Historic buildings are often blamed for their poor energy efficiency without considering their usually high constructional quality. What do we know about the real performances of these buildings? Energy retrofits in non-monumental and inhabited historic buildings are often guided by practical and operational needs rather than by their heritage significance. Can a value-based approach affect the improvement of energy efficiency? In a subarctic climate, even simple interventions can help to save a considerable amount of energy in historic buildings. To which extent the energy performances of the Bläckhorn houses could be increased without affecting their heritage values?

The impeding climate change challenge urges for a reduction of energy use in the built environment. Buildings account for nearly 40% of the total energy use and about 35% of the greenhouse gas emissions in Europe. EU member states are required to improve the energy efficiency of the existing building stock, for example by sharpening building regulations and developing enforcement schemes. Since energy efficiency retrofits can affect irreplaceable values in heritage buildings, heritage buildings are often excluded from mandatory demands aiming at reducing the energy use in buildings. However, saving energy have gradually become embraced by the conservation community and heritage buildings with are seen as part of the solution.

This licentiate thesis discusses the methods to identify heritage significance in a building and how the underlying theory determines different scenarios in a energy retrofitting process. The choice of conservation theory and conservation approach will affect the success the energy retrofitting process and determine how much the energy use that can be reduced. This thesis therefore suggests a framework to understand the different interpretation of the impacts that one could exert either by having an Objectivistic or Relative conservation value approach.. Based on this framework, a decision-support tool is developed to further detail the impacts of such approaches for different energy measures.

Other results show that a majority of reviewed research publications focused on the operational energy in a building and only a few were concerned with energy use over the entire life- cycle of a building. These analyses are used to evaluate where most energy savings can be made, and often pinpoint weak spots in the building’s envelope or technical system. If it was mentioned at all, the influence of cultural and historical factors on energy efficiency measures as applied to heritage buildings tended to be assessed only briefly. Indeed, the majority does not describe conservation principles or even mention the methodology used – if any – for assessing or defining heritage values. Instead, researchers often show an explicit (sometimes an implicit) understanding of conservation as essentially something that is not destructive of original construction material and hence the authenticity of a building.

This licentiate thesis is a compilation thesis, consisting of one separate sub-study, one literature review and an extended cover essay. The study is oriented towards a Swedish and European context, especially when it comes to climate conditions and discussions on building regulations and the theory and practice of architectural conservation. It addresses the growing research field of energy efficiency in heritage buildings and the thesis aims to contribute to an increased understanding on how the process of assessment and evaluation of heritage significance in buildings affects the making of heritage buildings more energy efficient. The main research question is: How do different approaches for assessing and evaluating heritage significance in buildings affect possible technical energy saving measures in heritage buildings?

Klimatförändringarna driver utvecklingen mot att energianvändningen i den byggda miljön behöver minska. Byggnader står för nästan 40% av den totala energianvändningen och cirka 35% av utsläppen av växthusgaser i Europa. EUs medlemsländer är bundna att förbättra energieffektiviteten hos befintliga byggnader, till exempel genom att skärpa byggreglerna och utveckla handlingsplaner. Eftersom energieffektiviseringar kan påverka värden i kulturhurhistoriska byggnader, är dessa ofta undantagna från krav som syftar till att minska energianvändningen i byggnader. Energibesparing och resurshushållning har gradvis blivit omfamnad av kulturmiljösektorn och kulturhistoriska byggnader betraktas allt mer som en del av lösningen på klimatförändringarna.

I licentiatavhandlingen diskuteras metoderna för att identifiera kulturhistoriska värden i en byggnad och hur den underliggande teorin påverkar olika scenarier i en energieffektiviseringprocess. Valet av bevarandeteori och bevarandestrategi påverkar framgångsfaktorn i energieffektivseringen och hur mycket energianvändningen i en kulturhistorisk byggnad kan minskas. I denna avhandling föreslås därför ett teoretiskt ramverk för att förstå effekterna av de olika kulturhistoriska bedömningar som kan göras, antingen genom att använda ett objektivistiskt eller en relativ syn på hur en en byggnads kulturhistoriska värden skapas och bäst bevaras. Utifrån detta teoretiska ramverk har ett stöd för beslutsfattande utvecklats för att ytterligare beskriva effekterna av de olika bevarandestrategiernas påverkan på implementeringen av olika energieffektiviserande åtgärder.

Andra resultat visar att en majoritet av de granskade forskningspublikationerna fokuserade på den operativa energin i en byggnad och bara ett fåtal gällde energianvändning under hela livscykeln i en byggnad. Dessa analyser används för att utvärdera var de flesta energibesparingar kan göras och ofta identifiera svaga punkter i byggnadens klimatskal eller tekniska system. Om det nämndes alls tenderade inflytandet av kulturella och historiska faktorer på energieffektivitetsåtgärder som tillämpas på arvsbyggnader endast att bedömas kortfattat. Faktum är att majoriteten av de genomgångna publikationerna inte beskriver bevarandeprinciper och inte nämner den metod som används för att bedöma eller definiera kulturhistoriska värden. Istället används ofta en explicit (ibland en implicit) förståelse för bevarande som i huvudsak något som inte förstör ursprungligt material och därmed autenticitet i en byggnad.

Denna licentiatavhandling består av en separat undersökning, en litteraturöversikt och en utökad kappa. Studien är inriktad på ett svenskt och europeiskt sammanhang, särskilt när det gäller klimatförhållanden och diskussioner om byggregler och teori och praktik för kulturhistoriskt bevarande av byggnader. Den är en del av det växande forskningsområdet energieffektivisering i kulturhistoriska byggnader och avhandlingen syftar till att bidra till en ökad förståelse för hur utvärderingen av kulturhistoriska värden i byggnader påverkar arbetet med att göra dem mer energieffektiva. Huvudforskningsfrågan är: Hur påverkar olika metoder för bedömning och utvärdering av kulturhistoriska värden energibesparande åtgärder i kulturhistoriska byggnader?

The paper presents results from the research project “Smart energieffektivisering av kulturhistoriska byggnader i kallt klimat”. The research is expected to develop, test and assess methods and solutions to increase the energy efficiency of heritage timber buildings in the northernmost part of Sweden.

The sub-arctic climate, with long, cold winters and mild summers, requires a significant use of energy, especially in historic buildings. This means that the difference in thermal performance and energy use with newly built buildings is greater and, at the same time, that even non-invasive interventions can be enough to save a considerable amount of energy with a limited impact on heritage values.

Valuable timber buildings from the late 19^th and early 20^th century are analysed in the cities of Piteå, Malmberget and Kiruna. Results are based on data collected on their energy and thermal performances, on the analysis of their constructional features and on the assessment of their heritage value.