nZEB Level Research Articles

A multi-criteria decision-making method for thermal insulation material selection in nZEB level questioned affordable multifamily housings

An affordable multifamily housing building archetype project was researched to improve the building envelope’s thermo-physical performance based on thermal insulation configurations to optimize the energy use, life-cycle cost, environmental impact, and thermal comfort with questioning nZEB concept. Five thermal insulation materials as extruded polystyrene (XPS), expanded polystyrene (EPS), rockwool (RW), glass wool (GW), and cellular glass (CG), were studied with four> attribute variations (thermal comfort, density, embodied carbon, and embodied energy) and five thickness variations (0.04, 0.08, 0.12, 0.16, 0.20 m). A total of 100 alternative scenarios> were obtained for the decision-making process, with four performance criteria to be evaluated in terms of energy, cost, thermal comfort, and environmental impact. Equal weights method (EWM), weighted sum method (WSM), and analytical hierarchy process (AHP) were examined for the multi-criteria decision-making among 46 scenariosvel. The analysis beyond the cost-optimal energy efficiency level, which varies between 64.89 and 72.62 kWh/m2a for primary energy use with a potential 10% further reduction, ensures the European Commission’s recommendations that target 50–70 kWh/m2a of primary energy use for housings in the continental climate to achieve nZEB. The best scenarios cover significantly the XPS at the head due to lover investment costs, where RW, GW, and EPS are followed among the best 10 scenarios, respectively. Besides, AHP provides a more effective distribution of weighting factors than the WSM where the best scenarios of the AHP covers 12 cm thermal insulation alternatives by balancing the investment costs and energy efficiency levels. The paper provides insight into thermal insulation material selection while searching for the advantages and priorities of thermal insulation materials’ attributes beyond the cost-optimal energy efficiency level to reach the nZEB range.

The energy renovation pathway to ZEB in Italy: Analysis of typical buildings and methodological aspects

The evolution towards high-energy efficient buildings is one of the most important challenges today and is in line with the objectives set by the new European Directive on the Energy Performance of Buildings (EPBD) which provides for the decarbonization of entire building stock by 2050. The study starts from the analysis of the current regulatory framework in Europe and Italy, highlighting the lack of homogeneity in the methods of transposition of European directives by the Member States already at the “nearly zero energy buildings” level (nZEB). Starting from these considerations, the critical analysis of the European and Italian context highlights the need to overcome the standards currently in force and investigate new perspectives for the design of high-efficient buildings in the direction of “zero energy and zero emissions”. For this reason, two residential and office buildings typologies are examined to confirm whether the net Zero Energy Building (ZEB) objective can be achieved through the legislation in force in Italy, starting from nZEB level. The study analyses the energy balance through dynamic simulations and evaluates energy needs of buildings and renewable energy production in order to verify the compliance to ZEB target, on yearly and monthly basis.

Re-considering the energy efficient retrofitting approach to question cost-optimality and nZEB under COVID-19 measures

The building energy performance has been highly studied in the last decades considering the indoor environmental quality, and sustainability indicators to examine energy-efficient cost-optimal, and nZEB building levels for different building typologies. However, since the start of the COVID-19 pandemic in 2020, the usage and operation of public spaces and buildings have evolved according to COVID-19 measures produced by the authorities. Social distancing measures and HVAC system measures affecting energy performance and indoor environmental quality of the public buildings are consequently necessary for building energy performance studies. Thereby, it is aimed at re-considering an energy-efficient cost-optimal retrofitting approach for a primary school building case, under the COVID-19 measures to recast an energy-efficient cost-optimal level and apply a cost-efficiency criterion to search for the measures adapted nZEB scenarios. COVID-19 measures affecting building energy performance, such as social distancing and IEQ requirements, were analysed. Then, probable ventilation rates were controlled by the infection probability method to satisfy the limit number for infection. Thus, pre-COVID-19 and post-COVID-19 variables regarding occupancy density and HVAC operation were determined for the calculation process. Besides, retrofit scenarios were shaped to improve optic and thermophysical properties of the façade, lighting, and HVAC systems performance. Then, energy, LCC, thermal comfort and IEQ performance of retrofit scenarios were calculated with a calibrated model. Results were evaluated by applying the cost-efficiency criterion to find out nZEB scenarios. It can be stated that distinct LCC and energy use increments occurred in the cost-optimal range and nZEB level.

Thermo-Energy Performance of Lightweight Steel Framed Constructions: A Case Study

The building sector continues to play an essential role in reducing worldwide energy consumption. The reduced consumption is accompanied by stricter regulation for the thermotechnical design of the building envelope. The redefined nearly Zero Energy Building levels that will come into force for each member state will pressure designers to rethink the constructive details so that mandatory levels can be reached, without increasing the construction costs over an optimum level but at the same time reducing greenhouse gas emissions. The paper aims to illustrate the main conclusions obtained in assessing the thermo-energy performance of a steel-framed building representing a holistically designed modular laboratory located in a moderate continental temperate climate, characteristic of the south-eastern part of the Pannonian Depression with some sub-Mediterranean influences. An extensive numerical simulation of the main junctions was performed. The thermal performance was established in terms of the main parameters, the adjusted thermal resistances and global thermal insulation coefficient. Further on, the energy consumption for heating was established, and the associated energy rating was in compliance with the Romanian regulations. A parametric study was done to illustrate the energy performance of the investigated case in the five representative climatic zones from Romania. An important conclusion of the research indicates that an emphasis must be placed on the thermotechnical design of Light Steel Framed solutions against increased thermal bridge areas caused by the steel’s high thermal conductivity for all building components to reach nZEB levels. Nevertheless, the results indicate an exemplary behaviour compared to classical solutions, but at the same time, the need for an iterative redesign so that all thermo-energy performance indicators are achieved.

Smart Thermostats for a Campus Microgrid: Demand Control and Improving Air Quality

Achieving nearly zero-energy buildings (nZEB) is one of the main objectives defined by the European Union for achieving carbon neutrality in buildings. nZEBs are heavily reliant on distributed renewable generation energy sources, which create new challenges associated with their inherent intermittency. To achieve nZEB levels, demand management plays an essential role to balance supply and demand. Since up to two-thirds of the total consumed energy in buildings is dispended for Heating, Ventilation and Air Conditioning (HVAC) operations, intelligent control of HVAC loads is of utmost importance. The present work aims to offer a solution to improve a building microgrids’ flexibility by shifting thermal loads and taking advantage of room thermal inertia. Innovation is present in using the internet of things to link several decentralized local microcontrollers with the microgrid and in the applicability of different control algorithms, such as the pre-emptive heating/cooling of a room. The developed solution relies on smart thermostats, which can be integrated into a building management system, or in a microgrid, and are capable of fulfilling the occupants’ need for comfort while complementing the building with needed power flexibility. The equipment is capable of controlling several HVAC systems to guarantee thermal and air quality comfort, as well as coordinate with a building/microgrid operator to reduce energy costs by shifting thermal loads and enacting demand control strategies. The smart thermostat uses an algorithm to calculate room inertia and to pre-emptively heat/cool a room to the desired temperature, avoiding peak hours, taking advantage of variable tariffs for electricity, or periods of solar generation surplus. The smart thermostat was integrated into a university campus microgrid and tested in live classrooms. Since the work was developed during the COVID-19 pandemic, special attention was given to the air quality features. Results show that smart HVAC control is a viable way to provide occupant comfort, as well as contribute to the integration of renewable generation and increase energy efficiency in buildings and microgrids.

Analysing energy upgrading projects of single-family houses towards a Norwegian nZEB level

As the existing building stock is responsible for high energy use and greenhouse gas emissions, energy upgrading projects have been acknowledged as crucial for the energy performance improvement of existing buildings, as well as for environment preservation and rational use of resources. The aim of this article is to investigate the definition of a nearly zero-energy building (nZEB) level for the energy upgrading of single-family houses. In particular, the findings from a research project, i.e., “energy upgrading of wooden dwellings to nearly zero energy level” (OPPTRE), are presented and discussed. A core task of OPPTRE was to carry out an architectural competition, where six interdisciplinary teams proposed innovative solutions for upgrading to a nZEB level representative Norwegian wooden single-family houses, from the period 1950-1990. The upgrading measures proposed in the OPPTRE competition focused on several aspects, such as architectural quality, indoor thermal environment, energy use/generation, carbon footprint, and cost effectiveness. General principles for a nZEB level achievement in upgrading projects are discussed in this article, as deducted from the evaluation of the results of the OPPTRE architectural competition. In particular, the focus is on examining the solutions proposed for upgrading building envelope and technical building systems. Energy use, energy generation, investment costs, and CO2 emissions are examined across the various OPPTRE projects, striving to define a trade-off among different parameters for the achievement of a nZEB level. The findings of this paper support the creation of knowledge in nearly zero-energy upgrading of wooden single-family houses, aiming to a more systematic definition of a nZEB level in such projects. This can be relevant for several stakeholders, such as governmental institutions, homeowners, builders, and private or public decision makers, towards the market uptake of nZEB upgrading by 2030.

Comprehensive parameters for the definition of nearly zero energy and cost optimal levels considering the life cycle energy and thermal comfort of school buildings

There has been an increasing interest in studying energy efficiency in buildings in the recent years, as they account for a significant portion of energy consumption and greenhouse gas emissions worldwide. While most of the studies focus on the buildings' operational phase, a substantial part of buildings' energy consumption is disguised as embodied energy. It is impossible to have a zero energy building, as it is necessary to use materials to build the building, and those materials need to produce and transport energy. Life cycle analysis is the utmost efficient method to assess how a building affects the environment. Notably, the impact of buildings on the environment across their lifespans are determined by some factors, which comprise materials, design, construction, use and demolition.The study aims to present the implementation of a life cycle approach and occupant thermal comfort during the school building's energy efficiency design. The study's principal objective focuses on the energy use and environmental impact linked to various alternatives of building envelopes in different climates. Within this context, a reference building located in three different climatic regions of Turkey is investigated. Two ranges of efficiency comprise the focal points of the study. Cost-optimal and nearly zero energy levels are defined for each city. In the hot climate, the cost-optimal scenario cannot improve the comfort conditions, whereas the nZEB scenario improves slightly in such a context. In temperate and cold climates, both strategies can improve comfort conditions. The share of embodied energy and carbon in the nZEB level can reach higher than 80 percent, whereas it is lower than 15 percent in the cost-optimal level.

Market based renovation solutions in non-residential buildings – Why commercial buildings are not renovated to NZEB

Renovation of commercial buildings was studied to analyze typical energy improvements and to determine the performance gap in relation to major NZEB level renovation. To provide input for Estonian long-term renovation strategy, building samples and interviews were used to study how the commercial property companies deal with the building renovation need in Estonia. Results show that in office buildings renovations improved energy performance marginally and a performance gap of about 40% existed after market-based renovation. About one third of trade buildings reached the NZEB level, but within the rest, the performance gap was about 50%. A common renovation cost was around 10 €/m2, but major renovation will need 130–150 €/m2. The main obstacle was the long, 20–30-year payback time and uncertainty of the measures for major renovation. This increases the risk of investment for a real estate company preferring max 10-year payback time. Interviewees pointed out, that tenants are not motivated to invest because the expected 2–3% saving in the sum of rental and energy cost seems invisible. To start the NZEB renovation, building owners recommended preparation of new energy or carbon taxes together with incentives and knowledge about energy efficient renovation.

NZEB and market-based renovation case study of an existing office building

The goal of decarbonizing the building stock in the EU requires a multi-fold increase of the current renovation rates. In Estonia, the non-residential building sector has had little or no public support to improve the energy efficiency. Therefore, it is essential to study the energy efficient and cost-optimal measures for non-residential building renovation to give guidance to real estate companies and other stakeholders about the renovation alternatives. Furthermore, crucial is to provide input to the government to develop the renovation grant and incentives for renovation. In this study, energy renovation measures and savings to improve the energy performance to NZEB level were identified in a large (16 990 m2heated area) office building. For that purpose, energy use was measured, simulation model developed and calibrated, feasible and more comprehensive energy improvements and costs analysed. The improvement of lighting, AHU, heating, installation of a 69 kW PV system, and window replacement was needed to achieve the goal with a primary energy use of 163 kWh/m2. However, some of the applied measures had long payback times of 40-70 years and are not realistic to be implemented without renovation incentives.

Thermomodernization of a Residential Building to NZEB Level

Directive (EU) 2018/844 of the European Parliament and of the Council of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency introduces a zero-energy building standard, for which the energy balance per year is zero, i.e. the amount of energy obtained from renewable sources is equal to the annual demand. Each Member State shall establish a long-term renovation strategy to support the renovation of the national stock of residential and non-residential buildings, both public and private, into a highly energy efficient and decarbonised building stock by 2050, facilitating the cost-effective transformation of existing buildings into nearly zero-energy buildings. To achieve energy consumption at an appropriately low level in an existing building, you must adjust the heat transfer coefficients of the building envelope and the demand for primary energy to the requirements of the Technical Conditions for year 2021. Renewable energy sources, primarily from the sun, will also play a key role. A computational example of a single-family building shows which partitions are best modernized, what thickness of thermal insulation materials should be used to properly reduce heat transfer coefficients, and which installation systems to use to reduce the potential energy index (EP). It is also depicted as to how much the demand for usable energy in the building will decrease. This article aims to show residents of single-family buildings what steps should be taken to reduce energy consumption and thus - operating costs in an existing building to a minimum.

Comparison of nZEB indicators for hotel renovations under different European climatic conditions

Abstract Hotels hold an important role in the energy efficiency policies of the European Union (EU), as they are typically ranked among the top energy consumers in the non-residential sector. However, a significant amount of the energy used in hotels is wasted, leaving ample room for enhancing energy-efficiency and resource conservation. Indeed, energy refurbishment of the hotel building stock is crucial in order to reach the nearly zero energy building (nZEB) status imposed by EU Directives for energy efficiency, and also an important pillar to achieve the energy targets for 2030 and the transition towards climate-neutral levels by 2050. A typical 4-star hotel in operation in Faro (Portugal) was used as a case study in order to establish energy performance indicators for nZEB hotels in three European cities, taking into account the influence of the climatic context, the technical feasibility and cost effectiveness of the best energy retrofit packages. The study started after the calibration of the building energy model by means of an energy audit and measured data, in order to have a baseline model that represents well the actual energy use of the hotel in the reference location. The building energy model was developed by using DesignBuilder/EnergyPlus software. The validated model was then used to assess the effect of the best retrofit interventions (energy efficiency measures and active solar systems) in order to set minimum energy performance requirements and to reach cost-optimal levels and nZEB levels for refurbished hotels. A significant energy-saving potential was found for the cost-optimal benchmarks, and the obtained nZEB levels can be achieved under technically and economically conditions for the selected cities: Faro, London and Athens.

ANALYSIS OF THE INFLUENCE OF ENERGY EFFICIENT HEATING MODES ON BUILDINGS ENERGY USE BASING ON THE MATHEMATICAL MODELING


 
 
 
 Global trends of increasing the buildings energy efficiency are aimed at reducing energy use to nearly zero consumption (nZEB). Achieving the nZEB level requires the implementation of a set energy-saving measures to improve the thermophysical properties of fences, building engineering systems and the use of renewable energy sources. One of low-cost and energy-efficient measures to increase the level of energy efficiency of buildings is the introduction of energy-efficient intermittent heating modes of buildings. Usually, this measure is appropriate and possible after the thermal modernization of the building. Determining the energy performance of buildings for the introduction of intermittent heating modes requires the use of mathematical models. The paper compares the application of different mathematical models and methods for estimating thermal energy savings in thermal modernization and implementation of intermittent heating modes based on the quasi-stationary model according to DSTU B A.2.2-12: 2015, stadium model created on the basis of RETScreen software and dynamic model 5R1C according to EN ISO 13790 and EN 13786. Heat-accumulation properties of building enclosures in RETScreen are not taken into account, in DSTU B A.2.2-12: 2015 - are taken into account for external enclosures, 5R1C - both internal and external enclosures are taken into account. The calculation was made for a residential building and a gymnasium located in the city of Kyiv. The introduction of a set of measures for thermal modernization of building fences will reduce heat consumption by 60 and 35% for residential building reinforced and gymnasiums, respectively. Introduction of intermittent heating modes for buildings after thermal modernization / modern buildings allows to save on heating more than 15% - determined on the basis of RETScreen program, 10% - on the basis of dynamic grid model 5R1C, 22% - on the basis of quasi-stationary method according to DSTU B A.2.2- 12: 2015, for a residential building and a gymnasium building located in Kyiv.
 
 
 

Benchmarking for realistic nZEB hotel buildings

The hotel sector is one of the most energy- and resource-intensive branches of the tourism business. Improving the performance of the hotel building stock, especially in the 4- and 5-star segment, is critical in order to reach the nearly zero energy building (nZEB) status imposed by the European Union's 2020 and 2030 targets, and also to meet the long-term objectives set by the Portuguese low carbon economy roadmap 2050.A typical 4-star hotel in operation in Portugal was used as a case study in order to establish realistic energy performance values for nZEB hotels, taking into account the feasibility and cost effectiveness of different intervention packages. The study started with a hotel energy audit, to assess the current energy situation, measuring detailed consumptions. A building model was developed using DesignBuilder/EnergyPlus software, which was validated using the measured data. The validated model was then used to assess the effect of different structured intervention packages (single and integrated measures), combining passive strategies and active technical solutions, also including renewable energy systems, in order to establish minimum energy performance requirements for the hotel stock (4- and 5-star category), taking into account optimal cost levels. The novel indicators may be used in the quantification of realistic nZEB levels for Portuguese hotels.

Cost reduction of the new NZEB Wooden building – case study of the kindergarten in Estonia

In this study the cost changes caused by the implementation of the nZEB solutions are calculated. The energy demand of a building was calculated according to the methodology for calculating the energy efficiency of buildings, using dynamic energy simulations. The financial calculations are based on the methodology described in Delegated Regulation (EU) No 244/2012 of the European Commission. The simulations and calculations for assessing the cost-effectiveness of technical solutions are based on the selected sample building. The energy efficiency solutions are derived by increasing/decreasing the insulation value of the building envelope in subsequent steps. Financial calculations were based on the investment needed to achieve the nearly zero-energy levels. The results for different combinations vary to a large degree. According to regulations new building must fulfill the low energy building (EPI class “B”) requirement without local production. The EPI value to fulfill the requirement in the cost-even range is reached in case of the GSHP and efficient DH. In case of the GSHP and efficient DH also the cost-optimal point is in the EPI class “B”. Overall the minimum ΔNPV values stay below the zero line in all the cases offering a range of opportunities to choose combinations to reach lover EPI compared to base case. The results of cost-effectiveness calculations for selected building with different combinations of structural solutions and heat sources show the possible different scenarios to reach nZEB level and the possible cost reduction.

Market review over the energy policies that stimulate, encourage and adopt building codes for nZEB promotion: the US and the European case

The building sector represents on a worldwide level, one of the larger energy consumers that should reduce its negative impact on the exterior environment. On a European level there are several directives that promote the transition to a decarbonized building sector that can be achieved by promoting the design and energy retrofit activity into nearly Zero Energy Building. The 2020 Climate and Energy Package, the 2030 Climate and Energy Framework and the 2050 Long-Term Strategy have the same goal, of cutting greenhouse gas emissions to admissible levels. In the United States the US Department of Energy alongside with the National Institute of Building Sciences set several targets for the development of a very energy efficient building stock. Thus, the paper offers an overview of the energy legislation implementation in European countries and in the United States, with a focus on identifying similarities and differences between the two regions. The first focus of the paper is on technical or legislative aspects identified in Europe and the United States in promoting nZEBs. Second, the definition of nZEB and its progress will be discussed and third several case studies will be discussed with the aim of identifying key points in achieving nZEB levels.

Realisation of energy performance targets of an old apartment building renovated to nZEB

Energy performance of buildings directive sets a goal to achieve a highly energy efficient and decarbonised building stock by 2050. In this study, a pilot nZEB (nearly zero energy building) renovation of an existing apartment building is analysed. nZEB criteria of new apartment buildings was set as the energy performance target in designing renovation solutions. The whole building envelope was additionally insulated with prefabricated modular panels and new service systems were installed. Measured energy consumption after the renovation showed that the pilot building fulfilled the minimum energy performance requirements for new apartment buildings, but nZEB target was not achieved. Measured heating energy consumption is 1.6 times higher (mainly because of the higher indoor temperature, supply air temperature, window airing, and higher ventilation airflow rates which methodology for heating energy calculations are not taken into account) and measured energy need for DHW is 4.4 times higher (mainly because of the real use profiles as well unexpected performance of solar collector and sewerage heat recovery system) than expected in building design. Results show that in renovation projects (also in new projects), occupant behaviour and the real use of building should be used as more realistic input parameters for designing energy performance. Distribution and circulation losses of air handling units, heating coils and DHW (domestic hot water) systems should be taken into account in the national energy calculation methodologies as service system heat losses can be a significant part of energy consumption at nZEB levels. If the renovated building would be used according to design methodology, the nZEB target can be achieved.

Business models for nZEB renovation of small wooden buildings

To achieve a sustainable building stock, it is necessary to focus on existing as well as new buildings. New houses built according to the Norwegian building code are close to nZEB (near Zero-Energy Building) level, but existing buildings contribute a significant share of the energy consumption, and the difference between new and older houses is increasing. As the renovation rate is low, it is important to include ambitious energy upgrading once a renovation project is undertaken. So far, however, there is almost no market for nZEB renovation of small wooden buildings. These buildings are challenging to renovate, and even more challenging to do so with ambitious climate targets. In effect, only half of the renovations in Norway include energy renovation. The demand for ambitious renovation depends on a value proposition that is understood by the customer. Novel and well-designed business models can be central tools for achieving this. In this paper, existing and potential business models for renovation of wooden housing are identified and analysed.This paper is based on the “Energy upgrading of wooden dwellings to nearly zero energy level” (OPPTRE) project. One of the activities for researchers, industry and public partners in OPPTRE is to identify, analyse and assess current business models, and develop novel approaches through collaborative workshops and interviews. The results are documented and elaborated upon by the research team before the next step, which is to test the most promising models.Previous research indicates that only a small share of Norwegian enterprises have changed their business model over time. Two of the reasons for this are lack of critical reflection on existing business models and fear of changing the status quo. A third reason is lack of knowledge of how to manage the transformation process. In the process of identifying existing and developing novel business models, the partners in OPPTRE explore new opportunities to promote ambitious energy upgrading. Their commercial performance is likely to increase through the focus on business model design. New business models may also help increase the uptake of innovative energy solutions in the renovation market for small wooden buildings.

Innovations for a carbon free Dutch housing stock in 2050

In 2017 the new Dutch coalition government agreed on high ambitions for the reduction of CO2 emissions to meet the Paris agreement and policies to achieve this were detailed in a Climate Agreement between the government and many stakeholder organisation in June 2019. In 2030 CO2 emissions have to be reduced to 49% compared to 1990. In 2050 we should have a CO2 emission free and energy neutral built environment. The existing housing stock plays a major role in the realisation of these goals. The Dutch housing stock comprises of 7.5 million dwellings. The majority of which has a rather bad thermal energy condition and are mainly heated by natural gas. All these houses have to be renovated to a nearly zero carbon performance. By 2021 yearly more than 50,000 new homes per year will have to be delivered on nZEB level without a natural gas connection and at least 50,000 existing dwellings will have to be made gas-free per year. These are steps towards 200,000 zero carbon renovations per year, a pace that is needed to make the entire stock carbon free in the 30 years up to 2050. To support these goals a large innovation programme is currently being developed. This paper presents the required innovations. Research on the impact of the policies and measures applied in the recent years point to the challenges that have to be overcome. A particular challenge is to realize the intended performance and really save energy and reduce CO2 emissions on a large scale.

Paving the Way to NZEB on two Historical Blocks in Lisbon Pombaline Quarter

The 1758 Lisbon Pombaline Quarter reconstruction plan is made of compact rectangular shaped residential blocks, built with a system that complies solid mass construction elements with a light wooden structure. If we take into consideration both constructive and architectural inherent features of the original Pombaline block, it shows the potential to achieve NZEB level if an energy retrofit strategy at a block scale is implemented, instead of the usual single building or fraction approach. The retrofit of historic buildings has raised questions regarding interventions depth and efficiency, as the impact on the built heritage value has to be residual or null while energy-related improvements must be noticeable. With this in mind, this paper intends to analyse and compare the result on energy demand and primary energy consumption of passive, active and BIST/PV systems packages implementation on two original blocks, with the challenge of minimizing the impact on case studies appearance. A Building Energy Simulation methodology is applied using the whole-of-building dynamic simulation software EnergyPlus. The results show that exterior envelope improvements can reduce up to 50% heating and cooling energy demands increasing thermal comfort at the same time. Finally, a combined VRF/Biomass heating solution display the best results on primary energy consumption while photovoltaic and solar thermal systems proved to have an essential role to achieve NZEB performance.

Towards upgrading strategies for nZEB-dwellings in Norway

Recent work suggests that upgrading in line with the Norwegian building regulations or by upgradingto the requirements of the national passive house norm, NS3700, can enable nZEB level to be achieved.The aim of this work is to explore the typical Norwegian housing typologies and some importantcharacteristics of the building envelope for these houses from different decades. The exploration involvedsurveying the typical technical qualities of Norwegian housing and how these have evolved – providingan important foundation to work addressing strategies and methods for upgrading dwellings to nZEBlevel in the next phases of the ongoing research project. The results of this work show that the buildingnorms and practices developed throughout the years have made dwellings more moisture resilient, withan increased drying-out potential through mechanical ventilation, control of the air change rate and theuse of more vapour-open wind barriers in the building envelope. Based on this, the work to follow willsuggest strategies for upgrading to nZEB level, solutions for upgrading building envelope componentsto high performance level and a methodology for risk reduction of moisture problems in the upgradeddwellings from the different decades.