Renovation measures aimed at recovering heat from exhaust air were assessed for their energy performance and economic feasibility in three Swedish apartment buildings. Case Building 1C‑HRV (Växjö) implemented a central heat recovery ventilation system, achieving the largest improvement: a 23% reduction in primary energy use (22 kWh/m²/year). Case Building 2DE‑HRV (Ljungby) installed decentralised HRV units, which increased energy consumption by 2 kWh/m²/year and incurred the highest annual service costs (SEK 14,000). Case Building 3EAHP (Växjö) integrated an exhaust air heat pump in one building, reducing primary energy use by 15% (12 kWh/m²/year) while supplying heat to three buildings on the premises. Despite the energy savings, none of the renovation measures were economically feasible under current conditions; the shortest payback period was 19 years for the exhaust air heat pump. Future integration of smart controls and photovoltaic panels could improve economic viability, particularly for Case Building 3EAHP, where operational patterns favour complementary technologies.

In response to volatile electricity markets and recent record increases in district heating prices in Sweden, smart control strategies for heating systems have become cost-effective solutions to reduce energy costs. By shifting electricity use for space heating and domestic hot water (DHW) to hours with lower prices, significant savings can be achieved. Historically, district heating has been a low-cost standard in Sweden, but recent price surges have led to the emergence of hybrid systems combining district heating with heat pumps, controlled by smart systems.This study evaluates five multi-family buildings renovated between 2022 and 2024. Systems using smart control for space heating and DHW were assessed, focusing on load shifting based on electricity prices. Investments in exhaust air heat pumps led to total energy reductions of 15 to 32 %, and district heating use decreased by 28 to 48 %. Additionally, billing power, which affects district heating tariffs, was reduced in most cases. Case Building 1 exhibited the highest reduction of 33 kW, translating to 2,768 EUR in tariff savings in 2023. Case Building 3 achieved savings of 1,880 EUR in 2023 and 1,557 EUR in 2024, with smaller reductions observed in other cases.It is essential to comprehend local pricing models to schedule heating during off-peak times. The current investigation has provided valuable real-world performance data on smart controlled hybrid systems under the new Swedish tariff structures. This data highlights the effectiveness of these systems in reducing energy costs, showcasing their potential for widespread adoption in regions with similar tariff models.

Renovation measures aimed at recovering heat from exhaust air were evaluated in terms of energy performance and economic viability across three case study buildings located in southern Sweden. The comparison involved both simple and detailed payback period analyses, assessing the impact of each measure on primary energy consumption and energy savings for each property.In Case Building 1 (Växjö), an FTX ventilation system with a central unit was installed. Case Building 2 (Ljungby) received an FTX system with decentralized apartment-based units, primarily to improve indoor climate conditions. In Case Building 3 (Växjö), an exhaust air heat pump was installed in one of the three apartment buildings. Although the pump extracts heat from a single building, it supplies heating to all three. The results indicate that the central FTX system in Case Building 1 achieved the greatest improvement in primary energy performance, with a 23% reduction corresponding to 22 kWh/m²/year. The exhaust air heat pump in Case Building 3 reduced primary energy consumption by 15% or 12 kWh/m²/year. Conversely, the FTX apartment units in Case Building 2 led to an increase in primary energy use of 2 kWh/m²/year. Service costs were highest for the decentralized FTX system in Case Building 2, estimated at SEK 14,000 per year (excluding VAT), compared to approximately SEK 3,000 per year for both the central FTX system and the exhaust air heat pump. All measures were found to be economically unfeasible under current conditions, with the shortest payback period—19 years—associated with the heat pump in Case Building 3. However, the integration of smart control systems and photovoltaic solar panels may enhance economic viability, particularly in Case Building 3 where the heat pump’s performance and usage patterns offer favorable conditions for such complementary technologies.

A wider deployment of nearly zero energy buildings (NZEBs) is expected to contribute to the transition to a decarbonized and energy-efficient building sector in Europe. This study proposed an integrated energy-economic analysis to exemplify the feasibility of NZEB renovation in temperate climate. A parametric analysis was performed to identify technical building system configurations that give minimum share of renewable energy systems contributing to NZEB level. Final energy savings, global costs and cost-effectiveness of renovating a building to NZEB level are analysed, considering active and passive energy efficiency measures (EEMs). The active EEMs included efficient water taps and heat recovery ventilation, and the passive EEMs encompassed insulations to roof, exterior walls and ground floor, and improvements of windows and doors. The building had initial final energy use of 133 kWh/m2 year for space heating, domestic hot water production (DHW) and facility electricity. The results show that NZEB level is achieved with active and passive EEMs, without renewable energy systems for scenarios with low discount rates and high future energy price escalations. The annual final energy use for space heating, DHW and facility electricity is reduced cost-effectively by 37-54%. Furthermore, increasing size of PV-system enhanced cost-effectiveness by lowering total global costs.

Residential energy consumption remains a significant driver of CO2 emissions in European buildings, demanding urgent action in the face of the climate crisis. While prevailing efforts have predominantly concentrated on enhancing energy efficiency and integrating renewable sources, addressing the climate urgency and resource constraints necessitates a paradigm shift towards sufficiency principles. Swedish statistics on Single-Family Houses (SFH) show that more than a third of households inhabit oversized spaces in aging buildings needing renovation. Sufficiency-oriented renovation strategies—optimizing, or reducing living areas per capita— present a promising avenue to achieve substantial energy reductions. This approach also opens the potential for space rentals, yielding combined energy and space efficiency advantages. In addition, the literature highlights reduced maintenance costs and potential urban housing crisis mitigation. However, practical implementation faces multiple obstacles.This paper investigates SFH owners' attitudes towards space-sufficiency interventions, focusing on living size preferences and identifying barriers and opportunities for sustainable housing. Through focus group sessions with SFH owners in November-December 2022, qualitative content analysis revealed that reducing living space per capita faces multifaceted challenges, despite potential benefits.These challenges encompass not only personal and psychological considerations but extend to economic, infrastructural, and policy barriers, including issues such as the potential breach of privacy, disruptions due to noise, dilemmas related to ownership and independency, disruptions to work-life dynamics, inadequate familiarity with sufficiency principles, and uncertainty imposed by space constraints. Strategic integration of sufficiency principles into energy-renovation policy alternatives necessitates a holistic approach that addresses these barriers, and some form of incentives may be needed to catalyze the adoption of sufficiency principles effectively.

A major challenge in building energy renovation is to cost effectively achieve notable energy savings. This paper investigates cost-effective passive energy-efficiency measures for thermal envelope retrofit of a typical Swedish multi-apartment building from the 1970s. Here, the use of different types of insulation materials for the retrofits of roof, exterior walls, and ground floor are analyzed along with changing windows and doors with varying thermal transmittance values. The cost-effectiveness analysis is based on the net present value of the investment costs of the energy-efficiently measures and the achieved energy cost saving. Different economic scenarios and renovation cases are considered in techno-economic analyses to determine the cost-effective energy-efficiency retrofit measures. The results indicate that improved windows reduce energy demand for space heating by up to 23% and yield the highest final energy savings. However, additional mineral wool roof insulation is the most cost-effective measure under all economic scenarios. This measure gave the lowest ratio of cost effectiveness of about 0.1, which was obtained under the stable scenario. The final energy savings that can be achieved in a cost-effective manner vary between 28% and 61%, depending on the economic scenario and renovation case. This analysis emphasizes the influence of different renovation cases and economic parameters on the cost effectiveness of passive energy-efficiency measures.

A municipal housing company located in the south of Sweden has energy renovatedseveral buildings with a total of 380 apartments to meet today’s energy standards. Several energyefficient technologies and solutions were implemented and the energy consumption for thesebuildings were lowered by 50%. One of the buildings functions as a demonstration building forinnovative solutions such as low temperature district heating, waste water heat recovery, andsolar photovoltaic and thermal (PVT) panels. The solar PVT panels are cooled down with themain purpose to increase the electricity production. The cooling medium for these panels iscirculated through two bedrock boreholes to dissipate the collected heat. The heat from theboreholes is then used for an electric heat pump to produce heat to send to the local districtheating company. The electricity produced is primarily used in the building. The objective ofthis paper is to assess the electricity production from real-life outdoor Photovoltaic-thermal(PVT) plant. The plant was installed on the roof top of an energy renovated multi-familyapartment building located in the south of Sweden. The cooling of the panels were turned on andoff to assess if the electricity production would increase or not. The electricity production didnot increase when the cooling was applied. The temperature measuring equipment which wasinstalled at the wrong position and was supposed to measure the temperature at the back of thePVT is needed to compare the efficiency of the PVT plant and draw further conclusions.

Den här guiden är en av tre guider som publiceras inom detta projektoch bygger på tidigare forskning, med syftet att utveckla kunskap och metoder för aktörer på efterfråge- och utbudssidan på marknaden för energieffektiv renovering av villor. Guiden ger en översikt över den kundresa som villaägare följer i sitt beslut att genomföra eller inte att energirenovera sin villa, och hur One-stop-shop (OSS) konceptet kan bidra med renoveringsresan.

A considerable share of the existing buildings in Europe has low energy performance and are expected to last at least for the next 50 years. The operation of these buildings causes high atmospheric greenhouse gases emissions, besides low thermal comfort for occupants. In Sweden, most of the existing buildings are residential, consisting of multi- and single-family houses. Large final energy savings can be achieved by integrating energy efficient measures (EEMs) to the thermal envelopes of these buildings. However, it is often a challenge to achieve a considerable energy savings and realize cost effectiveness simultaneously. This study investigates the effect of carbon taxes implementation on the cost effectiveness of EEMs applied to an existing multi-apartment building in southern Sweden. It explores the implications of different additional insulation thicknesses for exterior walls and roof, and high-performance windows and doors, for the final energy use and carbon dioxide (CO2) emissions of the building. The final energy savings of the EEMs are estimated through dynamic energy balance simulations and the CO2 emissions are calculated considering the full energy chains. The cost effectiveness of the EEMs are analyzed with and without carbon abatement costs considering the investment costs and associated net present value of costs savings of the EEMs. The results show that replacing the existing windows give the highest final energy savings, reducing the building’s space heating demand by 23 %. The cost optimal analysis without carbon abatement costs shows that all the analyzed thicknesses of roof insulation and high-performance windows are cost effective. Considering the carbon abatement costs altered the cost effectiveness of the EEMs, with exterior walls as well as ground floor insulations and door replacement becoming cost effective for certain thicknesses and U-values, respectively.