Comparing cost-optimal and net-zero energy targets in building retrofit

Ferreira, Marco António Pedrosa Santos; Almeida, Manuela; Rodrigues, Ana; Silva, Sandra Monteiro

doi:10.1080/09613218.2014.975412

Cited by 74 publications

(39 citation statements)

References 5 publications

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“…The first renovation package (Reference) comprises the reference situation from which the cost-effectiveness is going to be evaluated, as explained in Reference [24], and shown in Figure 1. The renovation package M1 comprises the application of an 8 cm thick layer of expanded polystyrene (EPS) in an external thermal insulation composite system (ETICS).…”

Section: Referencementioning

confidence: 99%

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Effect of Embodied Energy on Cost-Effectiveness of a Prefabricated Modular Solution on Renovation Scenarios in Social Housing in Porto, Portugal

2020

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A large-scale energy renovation intervention in existing buildings has been consistently presented as the most significant opportunity to contribute to achieving the European targets for 2030 and 2050. One of the key points for such achievement is the cost-effectiveness of the interventions proposed, which is also closely related to decent housing affordability. Prefabricated modular solutions have been pointed out as a pathway, but there are knowledge gaps regarding both its cost-effectiveness and its environmental performance. Considering a social housing multi-family building in Porto, Portugal, as a case study, this research employs energy simulations, a cost-optimal methodology and a life cycle analysis approach to assess the influence of considering embodied energy and emissions in cost-effectiveness calculations. In general terms, the hierarchical relation between calculated renovation scenarios remain identical, as well as the choice of the cost-optimal combination, which can reduce primary energy needs by 226 kWh/(y.m 2 ). However, embodied carbon emissions and embodied energy of the materials used in the calculations, which are indicative of the sustainability of such interventions, increase the energy and carbon emissions associated to each renovation package by an average of 43 kWh/(y.m 2 ) and 9.3 kgCO 2eq /(y.m 2 ), respectively.Sustainability 2020, 12, 1631 2 of 17 concepts were introduced, such as the nearly Zero-Energy Buildings (nZEB) [6], which are characterized by a high energy performance. The nearly zero or very low amount of energy required in these buildings must be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby [6]. Notably, according to this directive, Member States should ensure that from 31 December 2020, all new buildings are built as nZEB [6]. Although this timeline is considered to be determinant for the achievement of the EU targets, many of the current policies still have their main focus on new buildings, which some studies indicate as not being sufficient. The majority of the European building stock has more than twenty years old and present low energy performance [7]. Considering the significant energy reductions that can be achieved by cost-effective energy renovations and that the replacement rate of existing buildings by new buildings is only around 1% to 2% per year [8], there is significant potential for decarbonization of the building stock.To unlock this potential, it is necessary to promote a large-scale energy renovation throughout Europe. There are, however, significant and well-known barriers to overcome [9]. One of the most mentioned barriers concerns the cost of interventions, which is closely linked to the concept of housing affordability [10]. Cities of today are under different kind of constant pressures, such as gentrification and speculation in the housing prices, and some authors argue for the urgent need to guarantee affordable housing [11]. The question of affordabili...

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Section: Referencementioning

confidence: 99%

“…Cost-effectiveness threshold and identification of the cost-optimal renovation scenario. Source: Adapted from Reference[24].…”

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confidence: 99%

Effect of Embodied Energy on Cost-Effectiveness of a Prefabricated Modular Solution on Renovation Scenarios in Social Housing in Porto, Portugal

2020

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“…At the project level, time, money, and other resources are wasted because of reworks and poor construction performance caused by quality failures [31][32][33]. The quality of both energy performance and the cost optimality is necessary to promote and analyze in construction projects, as stated in several [34][35][36][37]. Hence, there is an urgent need to avoid quality failures in construction projects.…”

Section: Definitions Of Quality and Quality Failuresmentioning

confidence: 99%

Identification of Quality Failures in Building Energy Renovation Projects in Northern China

Qian

Meijer

et al. 2019

Sustainability

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Building energy renovations contribute significantly to energy sustainability and environmental protection. These advantages have increased the importance of renovating existing residential buildings in many countries. In China, the government has supported the energy-saving renovation of existing urban residential buildings since 2007. However, quality failures, which do not meet the technical requirements, occur during construction processes in building energy renovation projects. Although quality failures are regarded as a crucial problem in building energy renovation projects, the identification of quality failures and their sources, likelihood, impacts, and causes remain mostly unknown. This paper investigates the nature of quality failures in building energy renovation projects. A total of 25 quality failures were first identified through five cases, and interviews with six experienced construction professionals in China. A questionnaire survey was further conducted to evaluate the frequency of quality failures. The results show the nature of quality failures that arise during construction and their sources, occurrence frequency, causes, and impacts. The research reveals that quality failures are caused by defaults by workers; inadequate checking procedures; incomplete construction site surveys; inaccurate design work; fraud of construction companies; and inefficient cooperation between different departments. Above all, the behaviors of the main actors are responsible for poor construction quality. Additionally, emphasis on quality control during the renovation preparation stage is critical to ensure that quality failures are reduced in numbers and severity.

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“…Each scenario includes multiple commonly used renovation techniques (RT) that primarily focus on building envelope retrofitting. These techniques were summarized and extracted based on highly influential and frequently cited studies [6,[19][20][21][22]. The six renovation techniques are as follows: RT3 involves applying the additional insulation to the inside face of exterior wall, while in RT4 insulation is added to the interior wall (interior walls are those partition walls separating different rooms and space).…”

Section: Renovation Techniques' Targeted Energy-saving Goalsmentioning

confidence: 99%

Cost-Effective Options for the Renovation of an Existing Education Building toward the Nearly Net-Zero Energy Goal—Life-Cycle Cost Analysis

2019

Sustainability

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A comprehensive case study on life-cycle cost analysis (LCCA) was conducted on a two- story education building with a projected 40-year lifespan in College Park, Maryland. The aim of this paper was to (1) create a life cycle assessment model, using an education building to test the model, (2) compare the life cycle cost (LCC) of different renovation scenarios, taking into account added renewable energy resources to achieve the university’s overall carbon neutrality goal, and (3) verify the robustness of the LCC model by conducting sensitivity analysis and studying the influence of different variables. Nine renovation scenarios were constructed by combining six renovation techniques and three renewable energy resources. The LCCA results were then compared to understand the cost-effective relation between implementing energy reduction techniques and renewable energy sources. The results indicated that investing in energy-efficient retrofitting techniques was more cost-effective than investments in renewable energy sources in the long term. In the optimum scenario, renovation and renewable energy, when combined, produced close to a 90% reduction in the life cycle cost compared to the baseline. The payback period for the initial investment cost, including avoided electricity costs, varies from 1.4 to 4.1 years. This suggests that the initial investment in energy-efficient renovation is the primary factor in the LCC of an existing building.

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Comparing cost-optimal and net-zero energy targets in building retrofit

Cited by 74 publications

References 5 publications

Effect of Embodied Energy on Cost-Effectiveness of a Prefabricated Modular Solution on Renovation Scenarios in Social Housing in Porto, Portugal

Effect of Embodied Energy on Cost-Effectiveness of a Prefabricated Modular Solution on Renovation Scenarios in Social Housing in Porto, Portugal

Identification of Quality Failures in Building Energy Renovation Projects in Northern China

Cost-Effective Options for the Renovation of an Existing Education Building toward the Nearly Net-Zero Energy Goal—Life-Cycle Cost Analysis

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