Abstract
The paper presents a systematic approach to study energy renovation of a larger building stock at cluster level using categorization, classification into modules, life cycle cost (LCC) optimization, and bottom-up modeling. Seven-story clusters of slab and tower blocks were analyzed to investigate the techno-economic potential for energy efficiency measures (EEMs) of 401 multi-story apartment buildings constructed during the 1960s and ’70s located in two Swedish municipalities. Energy renovation with intention of lowest LCC and projected energy savings concerned the purchased energy for space heating and domestic hot water use allocated by different district heating (DH) tariffs. Different conditions for DH and performance indicators demonstrated code compliance. The LCC analysis revealed a rather small potential for cost-optimal EEMs on building envelopes. Incentives to gain LCC savings during energy renovation increased with a DH tariff with constant price rate throughout the year. A starting point for cost-effective energy renovations arguably would be clusters with 94 two-story and 160 three-story slab blocks, also requiring fewer EEMs to achieve thermal performance requirements. DH systems using industrial excess heat can improve buildings’ energy performance and reduce required EEM investment costs. The DH price level is shown to be a vital issue for cost-effective energy renovations.
Highlights
Reducing the energy use of the building sector in the European Union plays a central role to achieve projected energy and climate goals [1]
The aim of the study was to investigate the techno-economic potential for energy efficiency measure (EEM) of 401 multi-story apartment buildings constructed during the 1960s and ’70 s located in two Swedish municipalities by using different District heating (DH) tariffs
Data collected from the energy performance certificate (EPC) register, including building attributes and energy data, arguably the most complete dataset for joining additional datasets [39] and managed by the National Board of Housing, Building, and Planning (‘‘Boverket”), is further supplemented with data from the property register and geospatial information provided by the Swedish mapping, cadastral and land registration authority (‘‘Lantmäteriet”)
Summary
Reducing the energy use of the building sector in the European Union plays a central role to achieve projected energy and climate goals [1]. About 35% of the existing building stock is more than 50 years old and roughly 75% is energy inefficient compared to today’s performance requirements [2] For this issue, a concept of cost-effectiveness has set energy performance requirements for existing buildings subject to major renovations, where at least a cost-optimal balance between investments involved and energy costs saved should be achieved throughout the life cycle of a building [3]. While new buildings’ energy use follows modern code requirements, older stock consists mainly of low-performance buildings, for instance, constructed in the 1960s and ’70s before the appearance of performance requirements and with unrealized potential for energy savings [6] Many of these buildings are characterized by standardized solutions with industrial prefabricated constructions including uniform block designs with horizontal lines of windows or balconies, multiple stories and dwellings, and produced in neighborhoods with the same type all over a country [7,8,9]. Besides commonly used age and size classes to describe residential building stocks [10], the characteristics and occurrence in neighborhoods enables categories (or typologies) with regard to plan design of apartments [11] or urban zones of cities [12]
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