Energy Performance Certification: Misassessment due to assuming default heat losses

Ahern, Ciara; Norton, Brian

doi:10.1016/j.enbuild.2020.110229

Cited by 21 publications

(8 citation statements)

References 50 publications

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“…Low-performance and inefficient buildings are usually occupied by people with low incomes, suffering from fuel poverty [33] and facing financial difficulties that prohibit them from paying for the energy that is necessary to maintain a proper IEQ or for an energy renovation of their dwelling. Similar deviations were also observed in Irish houses, with actual energy savings of −22% for low-performance dwellings and even reaching up to −70% for high (very good) performance dwellings [34]. In the Netherlands, low-performance dwellings have much lower energy use, while the ones with high performance have a low energy use higher than calculated [35].…”

Section: Occupant Behaviorsupporting

confidence: 62%

Impacts on Indoor Thermal Comfort and Heating Energy Use in Hellenic Dwellings from Occupant Behavioral Reactions

Dascalaki¹,

Balaras²

2021

Applied Sciences

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In an effort to reduce the operational cost of their dwellings, occupants may even have to sacrifice their indoor thermal comfort conditions. Following the economic recession in Greece over recent years, homeowners have been forced to adapt their practices by shortening heating hours, lowering the indoor thermostat settings, isolating spaces that are not heated or even turning off their central heating system and using alternative local heating systems. This paper presents the results from over 100 occupant surveys using questionnaires and walk-through energy audits in Hellenic households that documented how occupants operated the heating systems in their dwellings and the resulting indoor thermal comfort conditions and actual energy use. The results indicate that the perceived winter thermal comfort conditions were satisfactory in only half of the dwellings, since the actual operating space heating periods averaged only 5 h (compared with the assumed 18 h in standard conditions), while less than half heated their entire dwellings and only a fifth maintained an indoor setpoint temperature of 20 °C, corresponding to standard comfort conditions. Mainstream energy conservation measures include system maintenance, switching to more efficient systems, reducing heat losses and installing controls. This information is then used to derive empirical adaptation factors for bridging the gap between the calculated and actual energy use, making more realistic estimates of the expected energy savings following building renovations, setting prudent targets for energy efficiency and developing effective plans toward a decarbonized building stock.

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Section: Occupant Behaviorsupporting

confidence: 62%

Impacts on Indoor Thermal Comfort and Heating Energy Use in Hellenic Dwellings from Occupant Behavioral Reactions

Dascalaki¹,

Balaras²

2021

Applied Sciences

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“…The authors analysed 1172 buildings for which both simulated and measured consumptions were known, and they found a gap of − 23% in the energy performance of building (pre-retrofitted); this gap became positive (2%) for buildings that had been renovated. Ahern and Norton (2020) performed a similar analysis and found that, for Ireland's single-family housing, the adoption of thermal default values (U-values) underestimated the energy performance of about 90% of the dwellings. The authors introduced a methodology, based on an Irish EPC database that is able to assess a realistic energy savings, after building retrofitting, using default U-values.…”

Section: Research Background and Gapmentioning

confidence: 97%

GIS-based urban energy modelling and energy efficiency scenarios using the energy performance certificate database

Mutani

Todeschi

2021

Energy Efficiency

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The EU building stock is 97% not energy efficient and the promotion of energy retrofitting strategies is a key way of reducing energy consumptions and greenhouse gas emission. In order to improve the energy performance of buildings, the European Union released the Energy Performance of Buildings and the Energy Efficiency Directives. The certification of the energy performance of a building is a central element of these Directives to monitor and promote energy performance improvements in buildings, with the aim of increasing their energy efficiency level, thereby reducing greenhouse gas emissions. This work evaluates the energy performance of existing residential buildings using the energy performance certificate database and identifies the more effective retrofitting interventions by applying an urban-scale energy model. The novelty of this study is that a new retrofitting database is created to improve the results of a building energy model at urban scale taking into account the real characteristics of the built environment. The here presented GIS-based monthly engineering model is flexible and easily applicable to different contexts, and was used to investigate energy efficiency scenarios by evaluating their effects of city scale. An urban energy atlas was designed for an Italian city, Turin, as a decision-making platform for policy makers and citizens. This energy platform can give information on energy consumption, production and productivity potential, but also on energy retrofitting scenarios. The results of this work show that it is possible to obtain energy savings for space heating of 79,064 MWh/year for the residential buildings connected to the district heating network in the city of Turin; these interventions refer mainly to thermal insulation of buildings envelope with windows replacement and allow a reduction in greenhouse gas emissions of 12,097 tonCO2eq/year.

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“…Energy Performance Certificates (EPC) provide important building-stock-related information not considered in the census but EPC data have flaws. For example, Ahern and Norton [11] concluded that models overestimate primary energy up to 70% by using default values for unknown parameters. In addition, Dall'O et al [12] found 24% EPC with unreliable information.…”

Section: Introductionmentioning

confidence: 99%

Building Stock Energy Model: Towards a Stochastic Approach

Panão

Penas²

2022

Energies

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This work uses the outcome of a computational tool that performs Energy Performance Certification (EPC) data processing and transforms raw data into comparable data. Multi-correlation among variables results in probability distributions for the most relevant form and fabric building parameters. The model consistently predicts the distributions for heating and cooling energy needs for the Lisbon Metropolitan Area, with an error below 7% for the first, second and third quartiles. Differences in the energy needs estimation are below 6% when comparing the seasonal steady-state with the resistance-capacitance (RC) model, which proved to be a robust alternative algorithm capable of modeling hourly user profiles. The RC model calculates electricity consumption for actual, adequate, and minimum thermal comfort scenarios corresponding to different user profiles. The actual scenario, built from statistics and a previous survey, defines a reference to evaluate other scenarios for the mean electricity consumption for space heating and cooling in the building units with those systems. The results show that the actual mean electricity consumption for heating (610 kWh/y) is slightly above the minimum (512 kWh/y), with 37% of building units potentially under heated. The electricity consumption (108 kWh/y) for cooling is below the minimum (129 kWh/y).

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Energy Performance Certification: Misassessment due to assuming default heat losses

Cited by 21 publications

References 50 publications

Impacts on Indoor Thermal Comfort and Heating Energy Use in Hellenic Dwellings from Occupant Behavioral Reactions

Impacts on Indoor Thermal Comfort and Heating Energy Use in Hellenic Dwellings from Occupant Behavioral Reactions

GIS-based urban energy modelling and energy efficiency scenarios using the energy performance certificate database

Building Stock Energy Model: Towards a Stochastic Approach

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