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Cost optimality in the refurbishment of public buildings towards nearly zero energy target : a case study : social housing, via Carema, Turin

Ilaria Malinverni, Noemi Morale

Cost optimality in the refurbishment of public buildings towards nearly zero energy target : a case study : social housing, via Carema, Turin.

Rel. Vincenzo Corrado, Simona Angela Alina Paduos. Politecnico di Torino, Corso di laurea magistrale in Architettura Costruzione Città, 2015


Reducing the building energy consumption to nearly zero energy level is one of the priority directions towards finding modern solutions to improve the energy performance of the building sector. In accordance with Directive 2010/31/EC and the Energy Efficiency Plan 2*8ll, Member States of the European Union shall draw up national action plans for taking the energy consumption and related GHG of new buildings close to zero but also for stimulating the refurbishment of the existing building stock into nearly zero-energy buildings. The provisions of the Energy Performance of Building Directive (EPBD) introduced in Article 9 the concept of nearly Zero-Energy Buildings (nZEB) stating that "by 31 December 2020, all new buildings are nearly zero - energy buildings; and after 31 December 2018, new buildings occupied and owned by public authorities are nearly zero-energy buildings". Although the EPBD Recast focuses on new buildings, the energy and C02 emissions associated with existing buildings refurbishments towards nZEB are worth being investigated because of their huge energy saving potentialities. Notably existing public buildings refurbishments play a crucial role in reaching energetic and environmental targets for Europe: they lead as example for private investors and should therefore endeavour to implement the nZEB energy targets fully.

This thesis work stemmed from the IEE RePublic_ZEB project, in which the Department of Energy was involved, representing the italian contribution. Among the many european projects that took place in the recent years, this is aimed at supporting the refurbishment of public buildings in southern Europe towards the nearly zero energy target. The nZEB concept regarding renovations, in fact, still does not seem to be easily applied by member countries: the past and current IEE programs efforts clearly show that required investments and optimal integration of the technologies suitable for the buildings renovation are among the major barriers to the implementation.

Furthermore, the lack of confidence in the real energy performance of nZEBs and the real risks associated to new technologies of the buildings industry and building owners seem to represent one of the keypoints the resolution of which could possibly solve the problem related to the high investments required in the process. In this context, the RePublic_ZEB proposal is focused on economically sustainable strategies and policies aimed at enforcing the refurbishment of the public building stock towards nZEB levels, according to EU 20/20/20 target. Thus the main objectives are to encourage the South-Eastern European countries to promote on the market a set of concrete technical solutions for the refurbishment of their public building stock towards the nearly zero energy target by increasing the involved key actors' confidence in nZEB, this way taking tangible steps to accelerate the renovation process and boost a real market demand to such buildings.

In order to achieve the above mentioned goals, the key actors addressed are meant to be builders and public building owners, policy developers (authorities), building technology industries and national professionals associations referred to the building industry (as architects and engineers).

The thesis mainly concerned Work Package n° 3 (Assessment of the status quo and analysis of opportunities for refurbishing public buildings towards nZEB) and Work Package n° 4 (Costs/ benefits analysis of the "packages of measures" for the refurbishment towards nZEB): these were also the steps taken in our work, applying cost optimality on the school case study.

Within the first step, the energy efficiency measures to be applied through deep refurbishment interventions on schools were detailed. The interventions were related to the building envelope, HVAC, DHW and lighting systems, including technologies based on the usage of RES. This stage was aimed to define a set of the most suitable building technologies (Energy Efficiency Measures) available on the italian market to reach the nZEB target for the public building stock. Local installers, manufacturers and technicians were involved in the market survey. We committed to being as precise as possible regarding the costs of the several interventions, going beyond the Piedmont Price List in order not to underestimate the evaluations and trying to provide data as close as possible to reality, assuming the real implementation of such a project.

In the following phase, corresponding to the WP4, the most suitable building technologies and technical systems were organized into packages of measures for the cost optimal energy and economic analysis. The aim of this step was to provide quantitative results in terms of saving energy and corresponding cost benefits that, in case of a real refurbishment, could increase builders' confidence in nZEB projects.

For the application of this methodology, an Excel format calculation tool was developed by the Department of Energy at the Polytechnic of Turin, consisting in a series of interconnected sheets able to provide, for each case study considered, the best cost-benefit technology solution aimed at reducing energy consumption, both for new buildings and existing ones undergoing total renovation. The energy assessment was conducted using a quasi-stationary methodology,

in accordance with technical specifications UNI/TS 11300-1/4, in order to predict global energy consumption for individual buildings; the economic assessment was conducted in accordance with standard UNI EN 15459 with the aim to predict the overall cost in a context of new construction or total renovation.

In conclusion, it can be said that, as the nZEB is not yet considered cost-efficient, cost optimal and nZEB requirements still have to be reconciled so that a smooth transaction from cost optimal requirements to nearly zero energy buildings could be guaranteed. This will require significant policy interventions, including increased support for research, development, deployment and demonstration of advanced building technologies. Such european projects are essential for policy makers as they can provide them tools to critically analyze the incentive system of our country, to identify any inconsistencies introduced in the recent past and to search for the opportunities offered by new technologies, in order to optimize the efforts. This is even more important for italian public existing buildings, for which nZEB renovations requirements have just been introduced and common practices still need to be assessed.

Relators: Vincenzo Corrado, Simona Angela Alina Paduos
Publication type: Printed
Subjects: R Restauro > RA Restauro Artchitettonico
S Scienze e Scienze Applicate > SH Fisica tecnica
Corso di laurea: Corso di laurea magistrale in Architettura Costruzione Città
Classe di laurea: UNSPECIFIED
Aziende collaboratrici: UNSPECIFIED
URI: http://webthesis.biblio.polito.it/id/eprint/4479





1.1.1 The EU Directive on the energy performance of buildings: EPBD 2002/91

1.1.2 The European 20 -20 -20 Targets

1.1.3 The EPBD recast


1.2.1 The national Law 10/1991

2.2.3 EPBD national implementation

2.2.4 EPBD recast national implementation towards the 2020 targets



2.1.1 Definition of the reference buildings

2.1.2 Identification of the energy efficiency measures

2.1.3 Calculation of the primary energy performance

2.1.4 Calculation of the Global Cost

2.1.5 Cost Optimal level of energy performance requirements

2.1.6. Undertaking of sensitivity analysis







3.3.1 Cross - country comparison


3.4.1 Before RePublic_ZEB

3.4.2 RePublic_ZEB





2.1.1 Regulatory framework and characterizing parameters

2.1.2 Italy and prospects for the envelope retrofit

2.1.3 Opaque envelope retrofit

2.1.4 Transparent envelope retrofit

2.1.5 List of technologies, parameters and costs


2.2.1 Italy and prospects for energy effciency

2.2.2 Technologies for energy efficiency - an overview

2.2.3 Emission retrofit

2.2.4 Control retrofit

2.2.5 Heating/cooling generation retrofit


2.3.1 Flat solar, Vacuum solar collectors retrofit

2.3.2 List of technologies, parameters and costs


2.4.1 List of technologies, parameters and costs


2.5.1 Regulatory framework and parameters characterizing

2.5.2 Air handling unit retrofit

2.5.3 List of technologies, parameters and costs


2.6.1 Regulatory framework and characterizing parameters

2.6.2 Artificial lighting sources retrofit

2.6.3 Lighting control retrofit

2.6.4 List of technologies, parameters and costs



3.1.1 The envelope refurbishment

3.1.2 The heating, cooling and DHW technical system refurbishment

3.1.3 The thermal solar, PV system, AHU and artificial lighting refurbishment


3.2.1 Calculation of the actual energy performance and referred actualized cost

3.2.2 Calculation of the cost-optimal solution

3.2.3 Search for the nZEB solution


3.4.1 Quasi-steady calculation results

3.4.2 Dynamic calculation results


Annex I. Insulating materials

Rockwool price list

Knauf price list

Styrodur price list

Annex II. Windows typologies

Annex III. HVAC and DHW system costs data

Biomass boiler (H/H+DHW)

District heating (H/H+DHW)

Air to water heat pump (H/C/DHW)

Water to water heat pump (H/C/DHW)

Annex IV. Thermal solar energy and flat solar collectors

Annex V. Photovoltaic system

Mono-crystalline module

Poly-crystalline module

Annex VI. Heat recovery ventilation an air handling unit

Annex VII. Calculation of lighting power density using different lighting sources and relative costs

Annex VIII – Republic _ ZEB partners



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Piedmont prices list

Rockwool product catalogue and prices list

Knauf product catalogue and prices list

Cabox prices list

Gypsotech product catalogue and prices list

Avproject Product catalogue and prices list

Aeremec prices list

FassaBortolo product catalogue and prices list

Torino Isolanti prices list

Navello Serramenti prices list

Unifissi Pvc Italia prices list

Viessman prices list

Hoval prices list ModaEdile prices list

Pasini prices list

Philips lighting and Siemens lighting prices list

Paradigmaitalia prices list

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