2.I.ii. Format of national transposition and implementation of existing regulations – OVERVIEW

The regulation of energy performance for existing buildings are included in the revised OIB Guideline 6, which was published in April 2019¹.

Following the requirements of OIB Guideline 6 (2019), the calculation method is based on Austrian Standards (ÖNORMs), created by the Austrian Standard institute which is represented in CEN; therefore, the standards used in the OIB Guideline 6 are in accordance with the European Committee for Standardisation.

The main indicators for the energy performance calculation of buildings (space heating demand, useful energy demand, final energy demand, primary energy demand and CO₂ emissions), maximum U-value of the building elements, geometry of the building, energy carriers, heating/cooling systems and domestic hot water systems as well as household appliances are defined in the OIB Guideline 6 or respectively in Austrian Standards (the OIB Guideline 6  refers according to user profiles for lighting, ventilation, humidification to valid Austrian Standards).

The determination of the required maximum space heating demand is based on the cost-optimal verification report².

The conversion factors for the energy carriers in the calculation of the primary energy demand have slightly changed to match the electricity mix of the Austrian market and are now expressed in CO_2eq instead of CO₂.

Table 5. The conversion factor of energy carriers in the OIB Guideline 6, 2019.

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In 2013, COBRACE⁴ replaced the 2007 EPB ordinance and transposed Directive 2010/31/EU. Several decrees (available at the Brussels Environment website⁵) describe the procedures to be followed and the calculation method and requirements to be met. A set of resources, e.g., a handbook, info-sheets and FAQ, are available at the Brussels Environment website⁶ for professionals in the construction sector. An evaluation of the EPB-legislation in the Brussels-Capital Region was carried out in 2015. In November 2015, the government approved the recommendations made by the real estate and construction sectors.

The calculation procedure is defined in an executive order adopted on 21 February 2013. The method is similar to those established in the Flemish and Walloon Regions respectively, and has been modified on 1 July 2017. The calculation method for primary energy already included the RES input, e.g., solar energy (thermal and photovoltaic), biomass heating, geothermal heating and heat pump systems, as well as passive cooling techniques. Changes implemented in July 2017 are integrated into the calculation, among others, for the prescriptions of the 'Ecodesign' Directive 2009/125/EC.

All new or considered as new⁷ residential building-units must respect the same primary energy requirement (PEC) expressed in kWh/m². For all new or considered as new non-residential buildings and units, the primary energy requirements are specified by means of a virtual reference building or unit, which coincides with the actual unit in geometry, floor area, orientation and functionality. Due to this reference building approach, each new building or unit has an individual energy performance requirement that takes its specific details into account. This requirement is also expressed in kWh/m² (Table 2).

The compliance of the procedure and energy performance requirements are checked by the Brussels Environment Office. The percentage of buildings not meeting one or more of the requirements is less than 2%. The fines are established in the COBRACE Art. 2.6.1. Most of the fines are imposed for not meeting ventilation requirements, whereas non-compliance with the primary energy requirement (E-level before 2015, PEC after 2015) is extremely rare.

Professionals responsible for monitoring new buildings and major renovation projects (called EPB advisors) must be accredited. To become accredited, they must have an architecture or engineering degree and have followed five (5)-day training sessions as well as retraining sessions when requested by the Brussels Environment Office.

Since 2017, an independent organisation performs an inspection of the quality of the work on a randomly selected sample of EPB-advisors. The EPB-advisor can be suspended if the requirements are not met.

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Energy performance requirements for new and renovated buildings in the Flemish Region first started in January 2006. The legislation was consolidated in the energy decree of 2009 (het Energiedecreet van 8 mei 2009⁵) and the energy law of 2010 (het Energiebesluit van 19 November 2010⁶). Each new building must fulfil requirements on energy performance (E-level) and insulation (U-values) as well as on the indoor air quality and thermal comfort (risk of overheating and ventilation).

The energy performance level or E-level sets the maximum allowed primary energy use for a building. The calculation includes, e.g., thermal bridges, shading devices and the infiltration rate. The airtightness measurement has to comply with the requirements of a quality-assurance scheme as part of technical specifications STSP71-3 (annex 6). Two energy performance methodologies are described in the energy law: one for residential buildings, and the other for non-residential buildings (with a new method based on CEN methods since 2017 for all non-residential buildings, substituting for the former method that covered only offices and schools). The primary energy factor for electricity is 2,5 and for other sources 1.

Every two years, all levels of requirements are evaluated by carrying out cost-optimal studies, and the levels are adjusted when needed.

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Since January 2017, the level of regulatory requirements has been tightened. The previous reinforcement dates back to January 2014. A new reinforcement corresponding to NZEB has been applied on 1 January 2019 for public buildings and will be applied on 1 January 2021 for all other buildings. An overview of the requirements is presented in Table 1.

Table 1. Overview of regulatory requirements (click for larger size).

Since 1 January 2017, all non-residential types of building units (called PEN units) and all residential building units (called PER units) are covered by a global calculation.

The threshold of the requirement for PEN units is variable (Table 2) and depends on the functional parts present in the unit and their respective sizes, according to the following formula:

Table 2. The values of the requirement levels per function E_{W, fcf f} ('2019' for public buildings only).

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According to the Energy Efficiency Act and the Law on Spatial Planning, any building investment project must meet the energy efficiency requirements. Contracting entities are obliged to obtain an EPC of the building. This applies to new building projects, and, in the case of existing buildings, to reconstruction, major renovations, overhauls and refurbishments. Compliance with prescribed measures is assessed through energy audits performed by companies registered with the SEDA.

Ordinance No. 7 of 2004 on the energy efficiency in buildings, as amended in 2017, defines the cost-optimal levels of minimum energy performance requirements for buildings (or for individual building units) as well as the energy efficiency technical requirements and indicators. It also defines the methodology for calculating the indicators of energy consumption and the energy performance of buildings, including those for NZEB. When designing new buildings and reconstructing existing buildings, the investments in energy efficiency are eligible provided that the materials and the systems are in compliance with legal standards and technical specifications.

Ordinance No. RD-16-932 of 23 October 2009, on terms and conditions for inspecting the energy efficiency of boilers and air-conditioning (AC) systems, defines the framework for the compliance checking process of technical building systems. The SEDA is the authority that imposes penalties for non-compliance. Although, by the end of 2019, no penalties had yet been imposed.

The EPBD is transposed within the Building Act (OG 153/2013, 20/2017, 39/2019, 125/2019 – which entered into force on 28 December 2019), which also lays down penalties to ensure that all the requirements of the EPBD are fulfilled. The Building Act further sets some secondary regulations, including:

• the Technical Regulation on the rational use of energy and thermal protection in buildings (OG 128/2015, 70/2018, 73/2018, 86/2018, 102/2020);
• the Ordinance on persons authorised to issue energy performance certifications of buildings, energy audits of buildings and regular controls of heating and cooling or AC systems of buildings (OG 73/2015,133/2015, 60/2020 – 30 May 2020);
• the Ordinance on the control of buildings EPCs and of reports on energy audits of heating and cooling or AC systems (OG 73/2015, 54/2020 – 14 May 2020)
• a new set of meteorological data – applied as of 1 January 2016
• the Ordinance on buildings energy audits and energy certification (OG 88/2017, 90/20³ ) which entered into force on 30 September 2017, implements information systems for the development of an energy certificate (IEC), managed by the ministry;
• the methodology for carrying out building energy audits, which entered into force on 30 September 2017.

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The methodology for calculating U-values is documented in the 'Guide of Thermal Insulation of Buildings' issued by the MECI, which is necessary to show compliance regarding building envelope minimum requirements and/or to use them as an input for assessing the overall energy performance of a building. The guide also provides the methodology for calculating effective thermal mass as well as general information about different insulating methods. The 'Methodology for Calculating the Energy Performance of Buildings' issued by the MECI documents all the algorithms and assumptions used to calculate energy performance and to issue an EPC. It includes the calculation of heating, cooling, ventilation, domestic hot water and lighting energy use, expressed in terms of primary energy, based on which the energy class is assigned to the building. The methodology was revised in 2015, mainly to address issues in certifying existing buildings. Both documents are based on CEN standards, and they are both mandatory, to be used to calculate the energy performance for all types of buildings, existing and new.

The MECI has decided to proceed with the revision of the methodology for calculating the energy performance of buildings. The project started in December 2018 and is scheduled to be completed in 2021 with the release of software that will simulate energy performance of buildings based on the new methodology. The revised methodology will be developed on the basis of the new CEN standards under mandate M 480 of the European Commission and Directive 2018/844/EU. The aim is to address misfits of the existing methodology and to include new technologies in view of implementing NZEB and enhancing building renovation.

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As mentioned earlier, the main act addressing building energy performance is the Energy Management Act. The energy performance is further covered by several additional decrees that address more specific technical issues:

• Decree No. 264/2020 Coll.¹ on building energy performance defines the methodology for the calculation of the energy performance of buildings, as well as energy performance indicators, parameters of the reference building, requirements for NZEB, primary energy factors and the obligation to display EPCs;
• Decree No. 193/2013 Coll.¹ on AC systems inspections defines the methodology and frequency of AC systems inspections;
• Decree No. 194/2013 Coll.¹ on heating systems and hot water distribution defines the methodology for heating systems dimensioning and energy efficiency assessment, as well as the methodology and frequency of heating systems inspections.

The energy performance calculation must be based on standards including:

• ČSN EN 73 0540³ on thermal protection of buildings, which specifies technical requirements for the design and verification of buildings (Table 1), including indoor environmental characteristics during their use.
• Technical standard ČSN 73 0331³ Energy performance of buildings - Typical values for calculation - Part 1: General and calculation data per month - which contains typical energy efficiency parameter values and intervals of technical building equipment efficiency, typical user profiles (based on, e.g., operational hours, ventilation, lighting and hot water preparation), climate data, etc.

Table 1. U-values set in the standard ČSN 73 0540.

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The BR2018 sets minimum energy performance requirements for all types of new buildings.

The minimum energy performance requirements set the limit in terms of maximum allowed primary energy demand for a building, including, e.g., thermal bridges, solar gains, shading, infiltration, ventilation, heat recovery, cooling, lighting (for non-residential buildings only), boiler and heat pump efficiency, electricity for operating the building as well as sanctions for overheating. The overheating penalty is calculated as a fictive energy demand, equal to the energy demanded by an imaginary mechanical cooling system, in order to keep the indoor temperature at 26°C. This additional energy demand is included in the calculated overall energy consumption of the building by the monthly based compliance checking tool 'Be18' (https://sbi.dk/beregningsprogrammet).

Renewable energy is included in the calculation. However, for all buildings, the maximum electricity production to be factored in from RES, e.g., solar cells and wind turbines, corresponds to a reduction of the need for supplied energy of 25 kWh/m² per year in the energy performance framework (primary energy).

For buildings to comply with the BR2018 and the voluntary low-energy class, it must be proved that they have a good thermal indoor climate during periods with higher-temperatures. The indoor temperature in residential buildings must not exceed 27°C for more than 100 hours per year, and 28°C for more than 25 hours per year. This can be done either through 'Be18' or via a dynamic simulation tool. In non-residential buildings, the building owner decides the temperature limits, and summer comfort must be proved using a dynamic simulation tool. Buildings that comply with the BR2018 requirements must have an airtightness that is better than 1.0 l/s.m² at a pressure difference of 50 Pa (for a 'low energy building' this must be better than 0.7 l/s.m²). Additionally, the airtightness for all buildings must be documented, e.g. through a pressurisation test. If there is no pressurisation test, a minimum airflow rate (1.5 l/s.m² at a pressure difference of 50 Pa) is to be used in the calculations.

The energy performance requirements for new buildings and major renovations of existing buildings are regulated by four regulations:

• The 'Minimum Energy Performance Requirements'¹⁰ regulation. This regulation applies for new buildings and buildings undergoing major renovations, and includes the main requirements, e.g., maximum allowable primary energy consumption, general recommendations and requirements for building envelope elements and technical building systems. General recommendations include a thermal comfort-based U-value recommendation, some requirements for technical building systems, e.g, for mechanical ventilation and some individual metering requirements. In addition to these, there are no specific component-based requirements for new buildings and for buildings undergoing major renovations. Numeric energy performance requirements are set only for the building's primary energy consumption. Besides that, the regulation gives the definition and primary energy performance value for low-energy buildings and NZEB. This regulation also includes primary energy factors of different energy carriers.
• The 'Calculation Methodology for Building Energy Performance Calculations' regulation⁸. This regulation includes all the necessary information about the calculation of the energy performance, e.g., efficiencies of heating and ventilation systems, infiltration airflows, and standardised patterns of use of the ten (10) different building types and other energy calculation input data, as well as detailed calculation formulas and guidelines for energy calculations. Basically, this regulation provides guidance on how to run dynamic energy simulations that result in energy needs as well as calculation rules and methods from energy needs to energy usage for delivered, exported and primary energy.
• The 'Requirements for Technical Building Systems that considerably affect Building energy efficiency' regulation¹¹. This regulation applies to buildings where smaller, rather than major, renovations will be performed. It specifies system performance requirements for building service systems that will be installed or replaced (heating, domestic hot water, ventilation, cooling, automation systems, local heat and electricity production systems).
• The 'Requirements for evaluating energy efficiency of technical systems that considerably affect building energy efficiency and data requirements to be presented to Building Register' regulation¹² describes and enforces actions to assess energy efficiency through inspections of systems with rated heating or cooling capacity over 70 kW installed, to be installed, replaced, or renovated in existing buildings.

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The minimum energy performance requirements have been revised for the construction of new buildings in line with the EPBD. The approach is based on the overall energy consumption, which takes the energy source (primary energy factor) into account.

The current minimum performance calculations for new buildings are based on a national calculation method that follows the main principles of CEN standards. Both CEN standards as well as other, more detailed calculation and simulation methods, can be used. However, the calculation and simulation methods must be documented for possible review.

Requirements are given as a fixed value (kWh_E/m² - primary energy).

The National Building Code of 2018 sets maximum values for overall energy consumption (E-values) calculated using the primary energy factor (Table 3; for weighting factors, see Table 2). The maximum values depend on the building type and, for single-family houses, on the area of the building. The new building code does not exclude any heating sources; however, the code encourages the use of RES and district heating, which have better primary energy factors than other energy sources. Other renewable energy sources (e.g., solar heating and power) are taken into account when calculating a building's primary energy needs. For single-family homes and apartment buildings it is possible to show compliance with the building code if the energy efficiency of the building components is within a given range; the set values concern building components (walls, windows, etc.) as well as system performance, and the building’s heating systems.

Table 3: Maximum values for primary energy consumption (E-value) in different building types.

Calculations also include thermal comfort requirements, indoor-air quality requirements and airtightness, thermal bridges and shading devices. Evaluation of airtightness is either based on a site test or on a quality control method accepted by the building industry.

Cost optimality

In the national report submitted to the European Commission in 2018, the average cost-optimal level of energy efficiency of buildings and building components for new buildings is 12% more efficient than the corresponding National Building Code regulations as set in the Ministry of the Environment Decree 1010/2017 (given in 2017). For renovations and retrofitting of existing buildings, the cost-optimal level of energy efficiency for buildings and building components is 4% more efficient than the National Building Code regulations as set in the Ministry of the Environment Decree 4/13 (given in 2013). The calculations were conducted for single-family homes, apartment buildings, office buildings and commercial buildings.

Table 4 presents the variation range between the cost-optimal level and energy regulations. The difference is calculated by weighting the result with the number of new and renovated buildings. The cost-optimal level is slightly more efficient than the demand of the regulations for both new buildings and renovated buildings. Differences are within the set 15% tolerance margin.

Table 4: Summary of cost-optimal tolerances in reference buildings, according to primary energy.

Building inspection authorities

An applicant for a building permit must ensure that the construction will fulfil the energy performance requirements. This is done through calculations whereby the results must be shown in the building permit documentation submitted to the municipal building inspection authorities responsible for inspecting the compliance of building permit applications.

The structure of RT 2012 is based on three performance requirements:

• The requirement for minimum energy efficiency of buildings, which imposes a limitation on energy demand (heating, cooling and lighting) based on the bioclimatic conception (B_bio) of the project, whereby the B_bio value has to be lower than a maximum value called B_biomax.

• The requirement for primary energy consumption, which imposes a limitation on primary energy consumed (C_pe) for the combined use of heating, cooling, domestic hot water, lighting and auxiliaries (pumps and fans), whereby the C_pe has to be lower than a maximum value called C_pemax.

• The requirement for summer comfort, where the ambient indoor temperature of the building, reached after the 5 hottest days of the year (T_ic), cannot exceed a reference level calculated for each project, whereby T_ic has to be lower than a maximum reference value called T_icref.

These three coefficients are calculated through TH-BCE⁵, a dynamic hourly methodology (calculations are run every hour of a full year), which describes each component of the building envelope, as well as its energy systems.

The values of B_biomax and C_pemax are absolute values, based on standard benchmarks depending on the building type (Table 1) and are modulated by local climate, altitude and immediate environment factors.

Additionally, in order to ensure that residential buildings are correctly built, qualified experts have to check that airtightness upon their completion does not exceed 0.6 m³/h/m² for single-family houses and 1 m³/h/m² for apartment buildings.

Finally, the RT 2012 includes requirements for renewable energy use. It takes different forms depending on the energy type, but it should amount to at least 5 kWh_EP/m².year.

Table 1. B_biomax and C_pemax for various new buildings typologies.

The regulations concerning the percentage of RES use – including possible substitute measures – are subject of the Renewable Energies Heat Act¹¹, last amended in 2010. Efficiency requirements for new buildings are set out by the Energy Saving Ordinance¹², which was subject to a major amendment in 2013. During the course of the 2013 amendment, the current requirements that came into force in January 2016 were already fixed.

The Energy Saving Ordinance refers to the German pre-standard DIN V 18599, version 2011-12, as the compulsory method for the proof of compliance and the calculation of the values for the EPC. Some international standards (e.g., EN ISO 13790, EN ISO 13789, EN ISO 6946) are included in the method; others are addressed by the ordinance in order to define additional requirements (e.g., EN ISO 13779 for AC system performance). The majority of boundary conditions and primary factors (Table 3) are given in the calculation standard as well.

Calculations of energy performance of new buildings are performed by experts using advanced software solutions. The 'Quality Community 18599'¹³ comprises the software companies and performs regular quality control of the software products. This is also a prerequisite for any software used for application in KfW funding schemes. In case that – on purpose or because of serious neglect – false calculations are performed or the building’s real design is different from the calculations, the expert risks a penalty of up to 50,000 €. Calculations performed during construction of new buildings are checked – mostly as samples – by the local authorities in charge.

Table 3. Primary Energy Factors; non-renewable fractions for use in energy performance calculations.

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The study of the cost-optimal levels of minimum energy performance requirements for buildings and building elements (Directive 2010/31/EU, Article 5) was coordinated by a steering committee formed by the YPEN and consisting of experts from the academic and scientific community, that was assisted by individual thematic working groups.

The steering committee completed the report for 'single-family' buildings, 'multi-family' buildings and 'office' buildings in August 2018.

After the completion of the cost-optimal study, the committee compared their results with the current minimum energy performance requirements and the YPEN revised the KENAK, posing stricter energy performance requirements. The revision of the KENAK was issued in July 2017 (M.D. DEPEA/oik. 178581, GoG B’ 2367/12.07.2017), while the revision of the relevant technical guidelines (5) of the TOTEE was issued in November 2017 (M.D. DEPEA/oik.182365, GoG B’ 4003/17.11.2017). The guidelines took into account all the existing CEN standards related to the energy performance of buildings.

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The requirement system has three levels, as far as new buildings and major renovations are concerned. Maximum permitted U-values are set for elements, as is a specific heat loss coefficient (W/m³K) as function of the surface to volume ratio. Also considered are losses from thermal bridges (using either the simplified or the detailed procedure), passive solar gains and the effects of shading devices. Finally, the specific yearly primary energy must not exceed the set limit depending on the type and use of the building. In Table 1 maximum permitted values are given for a few typical uses (residential, school, office), whilst in the case of mixed or other use, comparison with a reference building is to be used⁵. The requirement of the specific yearly primary energy need for NZEB will not depend on the surface to volume ratio anymore, only on the building function.

Table 1. The maximum values of the yearly E_p’s as function of the building.

The primary energy needs include heating, domestic hot water, cooling and ventilation, and for non-residential buildings also lighting needs. Airtightness measurements are not required, but the quality of windows is examined visually by experts on-site and the estimated infiltration is taken into account in the calculation. For new buildings and major renovations, thermal comfort and minimum requirements on fresh air supply are set, but relevant values are not included in the calculation procedure for certification. The calculation procedure refers to several European standards. NZEB level requirements are presented below in detail and the method of calculations is the following:

• At least 25% of the energy need of the building should be covered from RES, that is, compared to the calculated value of the specific yearly primary energy need. The 'renewable share' is defined as the quotient of renewable/non-renewable energy. During the calculation of the value of the energy need, the renewable primary energy need is not taken into account. Even if the specific primary energy consumption is less (e.g., half) than the threshold value, the building is not approved as NZEB unless the above 25% is fulfilled, which leads to extra measures in order to further decrease the non-renewable energy consumption;

• Regarding primary energy factors of district heating systems, the RES factors calculated by the heat distribution companies are published each year by the Lechner Nonprofit Knowledge Center⁶. If there is no data provided, the value e_distr=1.26 kWh/kWh is to be used. 

• For the calculation of the renewable share, the following RES factors should be used: e_RES=0.1 if the national electric grid is used; e_RES=1 if firewood, biomass, biogas, pellets or agripellets as well as solar, wind, water, geothermal, hydrothermal energies are used. 

For NZEB, detailed calculation or dynamic simulation is compulsory – these match the already available CEN standards.

The most detailed and comprehensive technical guidance document for energy experts is the book 'Building Energetics'⁷. This book is a step-by-step guide for professionals including legislative background, the calculation process of the asset method, the certification process and an analysis of existing buildings. A new up-to-date version of the book has been published in early 2017. In addition, the Prime Minister’s Office publishes technical guidance documents⁸.

Table 2. The primary energy factors in Hungary.

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For all new non-residential buildings, the 2017 NZEB Regulations require 60% reduction in the calculated energy use compared to the 2008 Regulations. This means an improved energy performance for the fabric, services and lighting specifications. The comparison reference and notional buildings were updated in 2017 thus the maximum coefficient values remain at 1.0. In 2017, a mandatory requirement for RES was introduced. RES must in general provide 20% of the primary energy use, however there is flexibility where the building is more energy efficient than the regulations. This typically corresponds to an A3 energy rating.

The Building Control section in each local authority is responsible for administrating the Building Regulations. SEAI is the issuing authority for the administration of the Building Energy Rating (BER) or EPC scheme. The DEAP and NEAP software, published by SEAI, are compliant with EN 13790 and serve the dual purpose of demonstrating compliance with Part L (Conservation of Fuel and Energy) of the Building Regulations and generating the BER or EPC and advisory report. Building control officers in local authorities are empowered to carry out inspections and, where necessary, undertake enforcement action in order to ensure compliance with the requirement to have an EPC. Penalties include a fine of up to 5,000 €, or up to three months in prison, or both. Enforcement is complemented by a “rights based” approach, focused on creating a compliance culture.

In DEAP, the electricity primary energy and CO₂ factors are calculated using forecasts from SEAI’s Energy Modelling unit.

Table 3: Electricity primary energy and CO₂ factors used in DEAP.

For non-residential buildings, the NEAP electricity primary energy and CO₂ factors are given in Table 4.

Table 4: Electricity primary energy and CO₂ factors used in NEAP.

Decree 26.06.2015 'Minimum Requirements' prescribes the calculation of the following energy performance indicators:

• Specific energy needs for heating (EP_H,nd), cooling (EP_C,nd) and domestic hot water (EP_W,nd);
• Energy performance indices for heating (EP_H), cooling (EP_C), domestic hot water (EP_W) and ventilation (EP_V) for residential buildings, plus lighting (EP_L) and transport (EP_T) for non-residential buildings, expressed in non-renewable and in total primary energy [kWh/m²];
• Global energy performance index EP_gl = EP_H + EP_C + EP_W + EP_V + EP_L* + EP_T* expressed in non-renewable and in total primary energy [kWh/m²] (lighting and transport services for non-residential building only);
• Minimum requirements are defined according to the 'reference building'⁶ (see Table 2 and Table 3). More severe parameters of the reference building entered into force in 2019 for public buildings and will apply to all the buildings as from 2021;
• A new building (or majorly renovated building) satisfies the minimum requirements if the specific energy needs for heating and cooling (EP_H,nd, EP_C,nd) and the global energy performance EP_gl are lower than those calculated for the reference building. New buildings further need to have a fixed minimum ratio of RES for the supply⁷;
• In case the required RES integration should not be feasible, the building has to adhere to a proportionally lower EP_gl limit value;
• The designer has to justify compliance or non-compliance of the project to minimum energy performance requirements in a report (model provided in one of the 2015 decrees). This validation is compulsory to obtain the construction licence. Controls from local authorities to check compliance are performed on demand.

Table 3. Reference building – technical building systems efficiency.

The energy performance calculation methodology is applicable for new and reconstructed⁶ or renovated⁷ buildings, as well as for existing buildings. The energy performance calculation methodology is described in Regulation No. 348. The regulations have determined that the building energy performance calculation procedure shall include thermal comfort, indoor air quality, infiltration, thermal bridges and shading devices. The building energy performance class indicator corresponds to the value, which was established according to the energy consumption used to heat the building. The energy performance calculation methodology is based on the corresponding CEN Technical Report CEN/TR 15615:2009 and on Standard EN ISO 13790:2008 conditions and includes references to the 16 other CEN standards. The energy performance calculation methodology uses the primary energy factor for the non-renewable part. Primary energy factor values are shown in Table 1.

Table 1. Primary energy factor values in Latvia.

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For residential buildings, the energy performance calculation for new and existing buildings is based on the calculated energy needs for heating, domestic hot water, ventilation and auxiliary needs. The results are expressed in terms of primary energy needs, heating energy needs and CO₂ emissions. Since 2016, photovoltaic production can be partly taken into account (only the part that is consumed by the technical equipment of the building).

Figure 4. Integration of photovoltaic production. SOURCE: Dr. Markus Lichtmess, Goblet Lavandier & Associés Ingénieurs-Conseils S.A.

For non-residential buildings, the energy performance calculation for new buildings is also based on the calculated energy needs for heating, domestic hot water, ventilation and auxiliary needs, but also on AC, lighting, humidification and dehumidification. For existing non-residential buildings, the real energy consumption (metered energy) is taken into account in the form of an established EPC based on the measured consumption. An EPC based on the calculated consumption is only foreseen for new constructions.

Besides minimum requirements for building envelope elements and technical equipment, all new residential and non-residential buildings have to fulfil global requirements expressed in heating energy needs and primary energy needs. These requirements are cost-optimal.

In order to raise consumer awareness of the strengthening of building energy performance requirements and more generally energy-efficient policies, the government is operating a consumer hotline through myenergy⁴ (the national body for information and advice in the fields of energy efficiency and renewable energy), providing support to all sectors with respect to building refurbishment. Further, the Ministry of Energy and Spatial Planning takes part in expert meetings and exchanges on best practices within the building sector. The ministry regularly updates FAQ documents that are made available to the public.

Concerning quality controls, the EPC database for residential buildings is an important tool. A plausibility check of each EPC is integrated into the software that is calculating the EPCs. Controls of EPCs take place regularly. A few experts who had issued EPCs containing errors have been penalised with a temporary ban, mandatory advanced training and the correction of errors in the EPCs.

The current minimum energy performance requirements came into force in 2016 and are laid out in a technical guidance document with two parts¹; Part 1 relates to the building envelope and overall energy performance, while Part 2 covers building services. For the first time, requirements for the overall energy performance were introduced, taking into account the specific building types so that buildings with the potential to achieve high-energy performance (e.g., single-family detached and semi-detached houses) are required to do so. Requirements were also tightened for specific elements such as glazing and roofs, while those parts designed to avoid overheating were retained.

The overall energy demand for buildings is set according to building typology. To maximise the potential for energy efficiency for buildings which have the potential of achieving low energy demand with the installation of solar renewables or other effective technologies, the maximum energy demand requirements are low. The national calculation methodology for the calculation of energy performance is the same as that for issuing EPCs so that both systems may be used to enable the effective enforcement and verification of requirements. The contribution of RES is factored in according to the actual benefit obtained. The second set of cost-optimal studies have given further insight, and the development of a new set of minimum requirements has been initiated.

Since the oil crisis in the 1970s, the Netherlands apply minimum requirements (also referred to as vangneteisen) for the thermal quality of the building envelope. In 2011 and 2012, a study has been carried out, to establish cost-optimal minimum requirements for existing buildings subject to major renovation. These requirements came into effect in 2013-2014. The minimum requirements for individual building components are listed in Table 2 for major renovations (25% envelope), and in Table 3 for minor renovations. These minimum requirements will become slightly more stringent, when the new energy performance requirements take effect as of 1 January 2021.

Table 2. Minimum requirements for building components for new buildings and major renovations (source: Building Decree 2012).

Table 3. Minimum requirements for building components for minor renovations (source: Building Decree 2012).

The Norwegian building regulation, mandatory since 2017, includes two options to fulfil the requirements. For non-residential buildings, only the first option is allowed.

• The first option contains specific energy limits for different building types. The requirements are set in kWh/m² useful energy demand per year within the building envelope, which considers heat recovery from ventilation systems but not system losses and energy export. If this option is chosen, a set of absolute minimum requirements must also be fulfilled.
• The second option (only for residential buildings) addresses different components of the building envelope as well as requirements for technical installations and solutions. The requirements will be considered fulfilled if it is proved that nine specific energy measures are applied. In addition to requirements concerning insulation and envelope airtightness, there are specific requirements for the heat recovery of ventilation air in the ventilation apparatus (yearly mean heat recovery rate) and the specific fan power (SFP) factor. These requirements are shown in Table 1.

In order to ensure flexibility in heating systems and to facilitate systems based on renewable energy, all buildings larger than 1,000 m² shall have flexible heating systems, normally waterborne, and must be able to utilise low-temperature heating distribution systems. Single-family houses need to have a chimney flue unless flexible heat distribution is installed or the house fulfils the requirements of the Norwegian passive house standard (NS 3700:2013). Installation of fossil fuels-based heating systems is not allowed. As Norwegian electricity production is almost exclusively based on renewable energy and fossil fuels are to be phased out from buildings, primary energy factors are not used in the regulations. To stimulate local renewable production when electricity is produced on site (more than 20 kWh/m² per year), the specific energy limit can be exceeded by 10 kWh/m² per year.

The Norwegian energy requirements are set for 13 different building categories. Indicatively, Table 1 shows the progress over time of certain aspects necessary to fulfil the Norwegian minimum energy requirements for commercial buildings, single-family houses and apartment buildings.

Table 1. Minimum energy requirements for buildings in Norway.

Table 2 shows the absolute minimum requirements that must be fulfilled if using the option of net energy demand limit.

Table 2. Minimum requirements under the “specific energy limits” option.

Since 1 January 2013, all new buildings are required to be controlled by an independent expert to a certain extent. For larger residential buildings and for non-residential buildings, the control will be more extensive than for single-family houses. Air leakage testing is mandatory for all building types and must be documented according to the current standard.

As the requirements regulate the net energy demand, no primary energy factors are available.

The Norwegian standard for the calculation of the energy performance of buildings is NS 3031, which is derived from EN 15603. The regulation of 2015 is based on the 2014 version of NS 3031.

A detailed description of the current regulation for new buildings is given in the CA EPBD Book 2016 country report of Poland.

The current methodology is described in the regulation on the methodology for the energy assessment of buildings and their parts, as well as for EPCs. The calculation leads to the determination of the index of annual non-renewable primary energy demand (EP) in kWh/(m²·year), which is necessary to check minimum requirements. Non-renewable primary energy factors are given in the regulation (Table 6).

Table 6. Values of correction factors (Wi) for non-renewable energy demand, for production and transfer of energy carriers.

The methodology also includes other values describing the energy performance of buildings:

• • • the index of annual demand for final energy (EK) in kWh/(m²year);
    • the index of annual energy needs (EU) in kWh/(m²year);
    • the index of CO₂ emissions;
    • the share of RES in the annual demand for final energy.

The general calculations of energy demand for heating, cooling and ventilation are based on CEN standards methods (e.g. EN ISO 13790 and other linked standards).

In January 2020, the Ministry of Development issued the 'Guide to Improve the Energy Performance of Buildings'⁴ (Figure 1). The guide describes the evolution of energy performance regulations in Poland. On the basis of multiple examples, it shows how to improve the energy performance of buildings. Moreover, the guidebook reveals national and regional incentives which support energy performance actions.

Figure 1. Cover of the 'Guide to Improve the Energy Performance of Buildings'.

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The current building energy performance legislation, which applies for both residential and non-residential buildings, bases the calculation methodologies on comparisons with reference buildings and includes the parameters presented in Table 1. The reference building is considered the same building as the one being evaluated, but with reference values for the building components and technical building systems, and without the contributions of RES and energy efficient solutions (heat recovery, etc.). Typically, these reference values reflect the minimum performance requirements of the building if it were constructed 'today'.

BuildingMain legislation requirementsRequirements included in calculations

Table 1: Requirements included in calculations.

The energy performance requirements established for residential buildings are set in terms of the useful energy demand needs for heating and cooling. The total primary energy for heating, cooling and domestic hot water is also limited to a maximum value. There is a minimum RES contribution required for domestic hot water based on a minimum solar thermal panel area for each building occupant.
Non-residential buildings have a minimum energy performance requirement, which limits the maximum primary energy for heating, cooling, domestic hot water, and lighting.

The revised 2013 requirements (both for residential³ and non-residential⁴ buildings) were established considering the comparative methodology framework for calculating cost-optimal levels published by the European Commission. A first cost-optimal study report⁵ issued in 2013, which addressed new residential buildings, concluded that legislation requirements were close to the cost-optimal levels and recommended not to change them. The cost-optimal study on non-residential buildings focused only on office buildings, which is considered the most representative building typology. The relevant report concluded that legislation requirements were significantly far from cost-optimal levels and recommended an update of the reference building characteristics to create legislation requirements which would fall within the range of the cost-optimal levels.

Most of the requirements were tightened again in 2016 following the planned update of the national legislation^3,4. These changes focused essentially on the improvement of the U-values for the whole building envelope and for the minimum efficiency regarding heating, cooling and domestic hot water systems.

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The EPBD has been incorporated into the Slovak legal system (act and ministerial decree). RES and heat recovery are now mandatory in new buildings. Requirements for the thermal protection of the envelope components and buildings are presented in the national standard STN 73 0540-2+Z1+Z2:2019¹. The revised standard (Z1) which came into force on 1 August 2016 and the consolidated standard which came into force on 1 July 2019 respect cost-optimality calculations. The process of the energy performance calculation is described in the Annex of the Ministerial Decree 364/2012² and refers to the standardised calculation methods. The whole package of CEN standards was implemented and included in Slovak Technical Standards (STN). More than 50% of the CEN standards were translated into the Slovak language and issued as STN EN standards. All umbrella standards and related technical reports were translated into the Slovak language. At the time of writing this report, the last of the umbrella standards and those related to thermal protection intended for translation have been submitted for publication. The monthly method is currently used for calculating the energy performance. The calculations are worked out separately for thermal protection and for the energy use for heating, cooling and ventilation, as well as for hot water preparation and lighting. Calculating primary energy is based on calculated delivered energy and primary energy factors. Non-renewable primary energy factors are provided in the Ministerial Decree 324/2016³, in force since 1 January 2017. The calculation procedure steps are described in the Ministerial Decree 35/2020⁴, in force since 10 March 2020. The non-renewable primary energy factor for electricity decreased from 2.764 to 2.2. Primary energy factors for district heating should be calculated following the Ministerial Decree 308/2016⁵.

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The Slovenian building codes PURES 2010, with the more severe minimum requirements in use since January 2015, are valid for all types of new buildings, residential and non-residential, while for public buildings (public investments), 10% more severe minimum requirements are imposed. However, new public buildings are front-runners in energy efficiency due to the financial incentives available for high performance NZEB as well as due to the first Decree on green public procurement⁷ that included low primary energy among the selection criteria for bids. However, the 2019 update of the Decree on Green Public Procurement (GPP)⁸ now explicitly states energy efficiency (together with the use of RES and low-carbon alternative energy sources) as one of the environmental goals, which shall also be reached when designing and constructing buildings.

Compliance with PURES 2010 must be demonstrated by fulfilling minimum requirements related to the maximum allowed specific transmission heat losses (Ht'), maximum annual heat demand for space heating (Qnh), maximum energy needs for cooling (Qnc) (for residential buildings only), and maximum primary energy for the energy systems operation (heating, ventilation and air-conditioning systems and lighting). Maximum U-values of the envelope elements are prescribed for all buildings. The use of at least 25% of RES is mandatory in all new buildings from 2010; alternatively, solutions that include a comparable impact on the primary energy are possible. The consideration of RES produced on-site is limited to the total final energy used for the building’s energy systems; the consideration of exported RES is subject to the integration of the new CEN EPBD standards into the revised rules.

The detailed minimum requirements and energy performance calculation methodology are given in the corresponding technical guidelines TSG-01-004⁹. A monthly energy calculation is predominantly used in practice, and energy modelling with the CEN EPBD standards validated tools is optional. Other minimum requirements cover thermal bridges, airtightness, shading, ventilation, heat recovery, cooling, lighting for residential and non-residential buildings, boilers and heat pump efficiency.

Compliance checking is done at the building permit stage, during the construction process and at building completion before the permission to use is issued. Full compliance is necessary for permission to use. Advanced control is in place for early NZEB, mostly as a precondition for financial incentives.

The energy requirements for new buildings are:

• Maximum heating need (QNH) per useful conditioned floor area (Au):
  • for residential buildings: QNH/Au ≤ 45 + 60 f0 – 4.4 TL (kWh/(m²year));
  • for non-residential buildings: QNH/Ve ≤ 0.32 (45 + 60 f0 – 4.4 TL) (kWh/(m³year));
  • for public buildings: QNH/Ve ≤ 0.29 (45 + 60 f0 – 4.4 TL) (kWh/(m³year))
• Maximum cooling need (QNC) per useful conditioned floor area (Au):
  • for residential buildings: QNC/Au ≤ 50 kWh/(m²year)
• Maximum primary energy (Qp) per useful conditioned floor area (Au):
  • for residential buildings: Qp/Au = 200 +1.1 (60 f0 – 4.4 TL) kWh/(m²year)

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Minimum requirements for the energy performance of buildings are established in Spain in the following document (CTE): https://www.codigotecnico.org/

This document contains the mandatory requirements to be followed, but it needs complementary guidelines which would allow for a better application of the regulatory requirements and a better understanding of the requirements by professionals.

These documents and guidelines can be found on the official website of the CTE in Spain, and in particular: https://www.codigotecnico.org/DocumentosCTE/AhorroEnergia.html

General methodology

The basic methodology adopted by the Spanish administration is common for both the energy performance certification of buildings and the establishment of minimum requirements for the construction of new and the renovation of existing buildings. In particular, it follows the specifications set out in the EPBD.

Following five years of operation, the methodology established in the regulatory reviews of 2013 tries to include some of the basic aspects set out in the European Standards for calculating energy performance, published in 2008.

Among others, the calculation methodology was corrected and partially adapted to consider European standards, as well as the use of indicators for different building typologies.

In general, Spain's calculation methodology is included in five (5) official computer software programmes, which are mandatory for energy certification, and are a very useful tool for compliance with the CTE.

The steps to be followed by this calculation methodology, and therefore by the computer software, are: firstly, to calculate the energy demand, both thermal and for domestic hot water and lighting; then, to calculate the energy consumption of the systems necessary to cover the demand. These calculations are made by integrating the building's needs on an hourly basis, and by a transitory time-scale regime.

With the above, the final energy consumption is calculated and extrapolated to non-renewable primary energy consumption and CO₂ emissions; these two indicators are finally evaluated and established by regulations.

Since the energy simulation software in Spain calculates the final energy consumption, it is necessary to have adequate conversion factors to obtain the non-renewable primary energy consumption and CO₂ emissions.

The primary energy factors and the methodology for obtaining them are published in the official document: https://energia.gob.es/desarrollo/EficienciaEnergetica/RITE/Reconocidos/Reconocidos/Otros%20documentos/Factores_emision_CO2.pdf

The electricity conversion factor is based on real data on fossil fuel energy consumption and energy generated from alternative sources. For the power plants of electricity production in Spain, it includes the energy losses during transportation and distribution. The statistical data of consumption used to generate this document includes the last seven (7) seasons. This document is also updated every five (5) years.

Cost Optimal

The limits established in the 2013 CTE for the consumption of non-renewable primary energy and for energy demand, were based on the Spanish cost-optimal calculations as foreseen in the EPBD. This document included cost-optimal calculations for all the building types included in the current regulations, for both residential and non-residential buildings, and for all climatic zones of Spain.

These calculations were revised in 2018 to release the 2019 requirements update.

All new buildings in Spain, as well as buildings being rehabilitated, meet the CTE’s established requirements, as this is mandatory for obtaining a building permit. It is thus not possible to build a building without complying with those regulations.

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Since September 2020, new requirements for energy performance apply in the BBR which now also includes regulations on accessibility, fire safety, hygiene, health and the environment (including ventilation and thermal comfort), acoustics and safety in use, as well as energy performance.

Energy performance regulations apply to all buildings, except for:

• greenhouses or similar buildings that could not be used for their intended purpose if these requirements had to be met;

• residential buildings used, or intended for use, for either less than four months per year or during a limited part of the year corresponding to an energy use estimated to be less than 25% of what would be the case in full-year use;

• buildings that do not require space heating or AC for most of the year;

• buildings where no space is intended to be heated to more than 10 ºC and where the need for energy for comfort cooling, hot water and building property energy use is low.

The requirements are differentiated per the following building types: single-family houses, residential apartment buildings and non-residential buildings. For single-family houses, requirements depend on the size of the building, where the smallest single-family houses are allowed a slightly higher primary energy number.

According to the building regulations (BFS 2011:6), new buildings must be designed in such a way that energy use is limited by low heat losses, low cooling demands, efficient use of heating and cooling, and efficient use of electricity.

Buildings must be designed so that the following information can be provided:

• the primary energy number (EPpet) (energy performance);
• the installed maximum electric power rating for heating devices (partial EPB requirement);
• the average air leakage of the building envelope (partial EPB requirement, only applicable for buildings of less than 50 m²);
• the average thermal transmittance (Um) of the building envelope (Aom) (partial EPB requirement), amounts, as a maximum, to the values indicated in Table 2.

Table 2: Maximum accepted primary energy number, installed electrical input for heating, average heat transfer coefficient and average air leakage, for single-family houses, apartment buildings and non-residential buildings (Table 9:2a, BBR 29).

The requirements in section 9:2 need not be met for buildings where the heating supply from industrial processes within the building covers most of the space heating needs. This shall be shown through a special investigation. For buildings above 50 m² , the requirement concerning air leakage is that the building’s climate envelope shall be so airtight that the requirements of the building’s primary energy number and installed electric input for space heating are met (BBR 9:26).

The primary energy number (EPpet) is calculated according to the equation below:

The energy demand for heating (Euppv) divided by a geographic adjustment factor at the municipal level is added to the energy demand for cooling (E_kyl), hot water (E_tvv) and auxillary energy (E_f), all of which are multiplied with a corresponding weighting factor (VF). The total weighted energy demand is finally divided by the area intended to be heated to more than 10 °C (A_temp).

The energy performance of the building is expressed as the primary energy number. The calculation of the primary energy number is based on the delivered energy and shall represent normal use. Values for normal use, for example indoor temperature and domestic hot water consumption are set in a regulation (BEN) as well as how to adjust measured values in case the use differs from the normal values. The geographical adjustment factor F_geo corrects the heating demand so that buildings in various parts of Sweden can be compared with respect to the difference in climate. The factor is derived as the fraction of heating demand in a type of building in the actual location to the heat demand for the same type of building in a reference location. The factor takes for example temperature, wind and insulation into consideration. The factor value is between 0.8 and 1.9. For Stockholm, the factor is 1.0. Replacing the previous climate zones with the geographical adjustment factor applied on the space heating energy made it possible to have a common national energy performance requirement as well as to use measured values for the determination of the energy performance.

Weighting factors are used for different energy carriers, see Table 3.

Table 3. Weighting factors (Table 9:2b, BBR 29)

BBR also requires that the building's primary energy number be verified, according to Boverket's regulations and general advice on determining the building's energy use in normal use and a normal year, BEN. See also 2.I.v.

Boverket is regularly monitoring the results of the cost‐optimal calculation requirements, in accordance with the EPBD. At these times the possible effects of further tightening of requirements are examined. In case of changed technical conditions, or favourable economic conditions, the regulations are tightened to correspond with what is calculated as cost-optimal.

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Part L of the Building Regulations addresses energy efficiency and transposes some of the EPBD requirements. To support the implementation of the Building Regulations, “Approved Documents” (ADs)⁷ have been published. These ADs are adopted for most projects to demonstrate compliance with Building Regulations. The ADs are:

• AD L1A and AD L1B for new and existing residential buildings; and
• AD L2A and AD L2B for new and existing non‐residential buildings.

The ADs include references to guides such as Eurocodes (EN) and set out five criteria for new buildings, as detailed in Table 1:

Table 1: New buildings requirements, England

Note that internal air quality is addressed under Part F of the Building Regulations: “Ventilation”.

Compliance, particularly with the first three criteria, is assessed using the National Calculation Methodology (NCM)⁸. For new residential units, the NCM is the Standard Assessment Procedure (SAP)⁹. An updated version (SAP 2012) was released in 2013 and encoded in privately‐owned software tools. For new non‐residential buildings, the NCM Modelling Guide¹⁰ was updated in 2013 and is encoded in both a Government‐approved software tool (SBEM) and privately‐owned software tools. Both NCMs use an Asset Rating approach, i.e. predicted energy consumption based on standardised thermal condition. These software tools are also used to produce EPCs on construction, sale and rent.

To support construction quality, the Government produced Accredited Construction Details (ACDs)¹¹. Alternatively, construction details calculated by qualified professionals may also be used. ACDs focus on improving thermal bridging and airtightness. Airtightness testing is required for most new residential and non‐residential buildings with some exemptions.

Building Regulations outputs are submitted to Building Control Bodies (BCBs)¹² for checking. Statistics on compliance, enforcement and penalties are not kept in England. “Competent Persons”, who are registered with a Government‐approved Competent Person Scheme¹³, are allowed to self‐certify that their work complies with Building Regulations as an alternative to a BCBs submission.

Cost-optimal assessment of energy performance requirements

A UK‐wide cost‐optimal report was published in January 2019¹⁴. The report compares Building Regulations¹⁵ (current at the time) in each UK jurisdiction to the calculated cost‐optimal levels.

Residential buildings

For new residential buildings, two reference building types were considered representative of developments in the UK: a 2-storey semi-detached house (Single Family Buildings) and a 4-storey apartment block containing 32 flats in total with two size variations (apartment blocks and multifamily buildings).

For existing buildings, the same two reference building types were adopted and modelled with the two most common wall construction types: uninsulated cavity wall and uninsulated solid wall, giving a total of four reference buildings for existing domestic buildings.

For new buildings, potential improvement measures were grouped into packages representing six different components of a building design: fabric, openings, thermal bridging, ventilation, heating and photovoltaic panels (PV). Five hundred and seventy-six (576) alternatives were considered for each reference building.

For existing buildings, improvement measures were analysed via two different methods: ‘Elemental analysis’ and ‘Analysis of packages’. Elemental analysis, the first analysis method, consisted of each measure being assessed individually. Assessed elements included fabric, openings and heating. In total, around twenty (20) options were modelled for each of the four reference building scenarios (the number varying by wall type). The second method of analysis, analysis of packages, assessed multiple measures implemented at one time. The measures selected for packages were those most commonly applied for renovation improvements to the building fabric and heating system. In total, eighty-one (81) options were modelled for each of the four reference building scenarios for the second method of analysis. Primary energy was calculated for each package/measure using the National Calculation Methodology (NCM). Costs were calculated for each model to identify cost-optimal levels which were then compared to standards (current at the time) in each jurisdiction (Tables 2 and 3).

> New residential buildings – The results show that standards were on average 4% more energy efficient than the cost‐optimal level for new houses, but, were 14% less energy efficient than the cost‐optimal level for new apartment buildings. In both cases, they are within the 15% range described in the cost-optimal methodology so there is no significant discrepancy between the cost optimal level and current standards.

Table 2: New residential buildings. Comparison of cost-optimal levels to current requirements for the UK.

> Existing residential buildings – In eight cases, the standards meet or improve upon cost‐optimal levels: cavity walls (semi-detached house & apartment building), solid walls (semi-detached house & apartment building), windows (semi-detached house & apartment building) and heating standards (semi-detached house & apartment building). Reference standards in two cases were below cost‐optimal levels: roof (semi-detached house & apartment building). The Government sets out in the report the next steps for reviewing current requirements for chillers and air handling units.

Table 3: Existing residential buildings. Comparison of cost-optimal levels to current requirements for the UK.

Non‐residential buildings

For new non‐residential buildings, seven reference buildings (representative of the building stock) were selected: office (natural ventilation and air‐conditioning), secondary school, hospital, hotel (air-conditioning), distribution warehouse and retail warehouse. A construction type (cavity wall or steel frame) was selected for each reference building.

For existing buildings, five of the seven building models used for new build were selected: office, secondary school, hospital, hotel (air-conditioning) and retail warehouse. Two baseline specifications were considered for each of the five buildings: a low energy (EE1) and a high energy (EE2) efficiency building based on benchmark data – hence 10 reference buildings considered in total.

A similar approach was adopted for measures and packages as for residential buildings. For new buildings, packages represent four different components of a building: fabric (including openings and thermal bridging), services, heating and photovoltaics (PV), therefore selecting one package from each component forms a complete building design. A total of one hundred and thirty-five (135) packages were considered for each reference building.

For existing buildings, common renovation and replacement measures with significant impact on energy use were selected. Renovation measures included: floors, walls, roofs and heating systems. Replacement measures included: windows, packaged chillers, central ventilation Air Handling Units (AHUs), Fan Coil Units (FCUs) and light sources (lamp efficacy). In addition to the elemental analysis, existing building measures were assessed on a package basis. Similar to residential buildings, primary energy was calculated using the NCM. Costs were calculated for each model to identify cost-optimal levels which were then compared to standards (current at the time) in each jurisdiction (Tables 4 and 5).

> New non‐residential buildings – In six building sectors, the reference standards were more energy efficient than the cost‐optimal levels: naturally ventilated office, secondary school, hospital, hotel (air-conditioned), distribution warehouse and retail warehouse. Reference standards in one sector were below cost‐optimal levels (air‐conditioned office). On average across all sectors, standards were 13% better than cost‐optimal levels.

Table 4: New non-residential buildings. Comparison of cost-optimal levels to current requirements for the UK.

> Existing non‐residential buildings – On average across all building sectors, the other walls, roof, windows and lighting standards met or improved upon cost‐optimal levels. The standards were below cost-optimal levels for cavity walls, heating, floors, chillers, and air handling units. For heating and floors, the differences are within the 15% range allowed for in the cost optimal methodology so there is no significant discrepancy between the cost optimal level and current standards. Furthermore, the cost optimal level for cavity walls is based on a 100mm cavity whereas most existing cavity walls have a 50mm cavity and fully filling (as per current standards) is considered to be very cost effective and worthwhile. The Government sets out in the report the next steps for reviewing current requirements for chillers and air handling units.

Table 5: Existing non-residential buildings. Comparison of cost-optimal levels to current requirements for the UK.

Wales adopted a similar approach to England, i.e., four “Approved Documents” (ADs)⁵ which provide a route to comply with Building Regulations. Five criteria are set for new residential and non‐residential buildings (Table 1).

Table 1. Requirements for new buildings, Wales.

As with England, these requirements are included in the National Calculation Methodology (NCM) and compliance is demonstrated by using Government-approved software. The Welsh Approved Documents allow the use of English Accredited Construction Details (ACDs) to demonstrate compliance. Wales adopted the English ACDs. Figure 3 gives an example. Compliance checks are similar to England, using Building Control Bodies (BCBs) and “Competent Persons”. See England report for details.

Figure 3. ACD for Timber Suspended Ground Floor. Extracted from ACDs for Masonry External Wall insulation.

Cost-optimal procedure for setting energy performance requirements

A UK‐wide cost‐optimal report, which addresses Wales, was published in January 2019⁶. See England report for details.

Northern Ireland implements the EPBD energy performance requirements through Part F “Conservation of Fuel and Power” of the Building Regulations. Technical Booklets F1⁷ and F2⁸ (Figure 3) support the implementation of the Building Regulations Part F¹. The booklets include references to guides such as Eurocodes (EN) and, similar to England, the Technical Booklets set out five criteria for new buildings, as detailed in Table 1:

Table 1. Requirements for new buildings⁹ and certain large extensions to non-residential buildings, Northern Ireland.

The National Calculation Methodology (NCM)¹⁰ implements these criteria. For domestic units, the Standard Assessment Procedure (SAP 2009)¹¹ is used, and for non-domestic buildings the Simplified Building Energy Model (SBEM V4.1) or approved Dynamic Simulation Models (DSMs) are used. Both domestic and non-domestic methodologies use predicted energy consumption and provide an Asset Rating for EPCs on construction, sale and rent.

The use of Accredited Construction Details (ACDs) is permitted. The English ACDs have been adopted in Northern Ireland¹². Figure 4 gives an example. Airtightness testing is required for most domestic and non‐domestic developments with some exemptions.

Building Regulations applications are submitted to local District Councils for checking and enforcement. Building Control Officers check compliance, which includes site inspections, and they have the power to take enforcement action.

Figure 3. Technical Booklets F1 & F2, Conservation of fuel and power in dwellings & buildings other than dwellings.^7 8

Figure 4. Illustration from ACD for Pitched Roof. Extracted from ACDs for Masonry External Wall Insulation.

Cost optimal procedure for setting energy performance requirements

A UK‐wide cost‐optimal report, which addresses Northern Ireland, was published in January 2019. See England report for details.

The following Technical Handbooks provide guidance on how to meet energy requirements set under the Building Regulations: the “Technical Handbook Domestic”² (for new and existing domestic buildings) and the “Technical Handbook Non‐domestic”³ (for new and existing non-domestic buildings). They include references to best practice guides, e.g. Eurocodes (EN).

Mandatory functional standards set ten criteria for new domestic and non‐domestic buildings (Table 1).

Table 1. New buildings criteria, Scotland.

The Technical Handbooks provide guidance to calculate the Target Emission Rate and reference the “Scottish Building Services Compliance Guides”^{7 8}, which recommend minimum standards for Technical Building Systems.

For domestic buildings, the Standard Assessment Procedure (SAP⁹) 2012 is used to calculate energy performance, demonstrate compliance with Building Regulations, and produce EPCs. For non‐domestic buildings, the Simplified Building Energy Model (SBEM) 2014 is used which implements the National Calculation Method (NCM) Modelling Guide¹⁰. The UK Government has developed the SBEM software, which is available free of charge. Government-approved, proprietary software tools may also be used for complex buildings. SAP, SBEM and proprietary software tools use calculated energy consumption based on standard conditions.

Scottish Accredited Construction Details (ACDs¹¹) may be used to assist with compliance. ACDs focus on providing insulation continuity at junctions (thermal bridges) and airtightness (e.g. Figure 3).

Figure 3. Illustration from ACD for Pitched Roof. Extracted from ACDs for Masonry External Wall Insulation.

The 32 Local Authorities in Scotland are appointed by Scottish Ministers as “verifiers” for their respective geographical area and they are responsible for the operation of the building standards system. As verifiers, they are responsible for granting permission for building work, undertaking reasonable enquiry to establish compliance and issuing a completion certificate before occupation.

Cost optimal procedure for setting energy performance requirements

A UK‐wide cost‐optimal report, which addresses Scotland, was published in January 2019. See England report for details.