m executive summary: 2 [¦ 300 500 - republic zeb · executive summary: nzeb measures in reference...

RePublic_ZEB © 2016

EXECUTIVE SUMMARY:

NATIONAL RESULTS FROM APPLYING TOOLS TO THE REFERENCE BUILDINGS

Authors :

Vincenzo Corrado & Simona Paduos Politecnico di Torino (POLITO)

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Energy Performance EPP,gl,nren [kWh/m2]

Executive summary: nZEB measures in reference buildings

RePublic_ZEB © 2016 of 13 21/12/2016

RePublic_ZEB Project

Year of implementation: 01/03/2014 - 31/08/2016

Website: www.republiczeb.org

Project consortium

BME WP3 Leader

BRE WP6 Leader

BSERC WP2 Leader

CRES Partner

CTI

WP1-WP7 Leader Coordination

EIHP Partner

URBAN-INCERC Partner

IREC Partner

LNEG WP5 Leader

MACEF Partner

POLITO WP 4 Leader

ZRMK Partner

http://www.republiczeb.org/

Executive summary: nZEB measures in reference buildings

RePublic_ZEB © 2016 of 13 21/12/2016

Project overview The RePublic_ZEB project is focused on the energy and CO2 emissions associated with existing public buildings and their refurbishment towards nZEB.

The core objective of the project is to:

Define costs-benefit optimized “packages of measures” based on efficient and quality-

guaranteed technologies for the refurbishment of the public building stock towards nZEB that

are standardized and adopted by builders and building owners.

From this stems three basic objectives: (i) State-of-the-art assessment of the public building stock through a country-specific

evaluation of the energy consumption and CO2 emissions;

(ii) Define reference buildings; and;

(iii) Develop a common framework and a harmonized methodology for the definition of a nZEB concept for public buildings.

Acknowledgement The authors and the whole project consortium gratefully acknowledge the financial and intellectual support of this work provided by the Intelligent Energy for Europe – Programme.

With the support of the EUROPEAN COMMISSION – Executive Agency for Small and Medium Enterprises implementing the Intelligent Energy for Europe Programme

Legal Notice

The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission is responsible for any use that may be made of the information contained therein.

All rights reserved; no part of this publication may be translated, reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the written permission of the publisher. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. The quotation of those designations in whatever way does not imply the conclusion that the use of those designations is legal without the consent of the owner of the trademark.

Executive summary: Refurbishment best practice and technologies

RePublic_ZEB © 2016 of 13 21/12/2016

Executive Summary

This document is one of a series of executive summary of the core deliverables of the RePublic_ZEB project. This is a summary of the third deliverable in Work Package (WP) 4. The flow chart below shows its context in the overall project.

1. Objective The objectives of this report are to:

Calculate the primary energy performance and the related global costs of the reference

buildings in each partner country before refurbishment;

Identify the cost-optimal package of energy efficiency measures;

Investigate at least two packages of measures for each reference building, suitable for the

nZEB retrofit.

Identify trends between the results for the reference buildings in each country.


RePublic_ZEB © 2016 of 13 21/12/2016

2. APPROACH

2.1 ENERGY PERFORMANCE AND GLOBAL COST BEFORE REFURBISHMENT

The overall approach to calculate energy performance and global costs and to identify the packages of measures that deliver nZEB is described in the previous summary report.

Before the building refurbishment, the following data need to be collected:

Energy performance of the current state of the building in terms of renewable, non-renewable and total primary energy

Actualized global costs

The renewable and the non-renewable components of the building energy performance were calculated by multiplying the calculated yearly energy consumption by the corresponding primary energy factors as defined at national level.

The actualized costs also refer to the reference building before refurbishment. Therefore the investment costs are zero, and only the running costs (i.e. operating and the maintenance and energy) are considered.

2.2 COST-OPTIMAL ENERGY PERFORMANCE AND GLOBAL COST

The cost-optimization procedure in the common tool identifies, among all the possible technical solutions, the most cost-effective one. This is the set of technologies – building envelope and technical systems – that ensure that the global cost is at a minimum.

It is possible that for certain reference buildings, the cost-optimal retrofit solution is not a major renovation, but just involves a few retrofit measures, e.g. window and/or the heat generator replacement only.

The optimization procedure also considers that each single energy efficiency measure (EEM) may not be implemented and, therefore, the building system does not change with respect to the starting conditions. Level 1 of the EEO corresponds to this situation (Figure).

Figure 1. Optimization procedure sheet

1 2 3 4 5 1 2 3 4 5

N.N.

paramatersParameter/Option Symbol

No.

EEO

1 1 Thermal transmittance Up 4 0,27 0,24 0,21 0 44,21 46,55 48,95

2 1 Thermal transmittance Up,u 5 0,30 0,26 0,22 0,19 0 29,85 31,13 39,88 42,40

3 1 Thermal transmittance Ur 5 0,26 0,24 0,21 0,19 0 56,32 57,37 69,03 75,69

4 1 Thermal transmittance Uf 5 0,28 0,24 0,21 0,19 0 28,62 31,69 34,90 38,15

5 1 Thermal transmittance Uw 5 1,47 1,34 1,08 0,88 0 244,33 292,40 397,75 387,04

6 1 1 fix; 2 movable 2 2 0 372,5

7 1 Energy efficiency ratio at design conditions EER 3 5 6 0 250932 261956

8 1 Generator efficiency at design conditions ηgn 5 1,1 0,9 0,88 4,3 0

9 1 Generator efficiency at design conditions ηgn,Pn,W 3 0,98 2,6

10 1 Generator efficiency at design conditions ηgn 4 1,1 1,1 0,9 0,88

Coefficient of performance at design conditions COP 4,3

Energy efficiency ratio at design conditions EER 3,1

12 1 Surface of solar collectors m2 5 198 224 231 275 0 122454 142152 246036 263610

13 1 Peak power kWp 5 10 18 26 45 0 10187 17975 25387 44075

14 1 Heat recovery efficiency ηr 0

15 1 1 Zone; 2 Ambient; 3: 1+Climatic; 4: 2+Climatic 1 4 81120

16 1Specific luminaire power (W/m

2)

(UNI EN 15193)PN 0

17 0

LIGHTING SYSTEM

GENERATOR FOR DHW

COMBINED GENERATOR FOR SPACE HEATING

AND DHW, AND APPROPRIATE EMISSION

HEAT PUMP FOR SPACE HEATING, DHW AND

COOLING, AND APPROPRIATE EMISSION

SYSTEM

THERMAL SOLAR SYSTEM

PV SYSTEM

SOLAR SHADING SYSTEM

CHILLER

GENERATOR FOR SPACE HEATING AND

APPROPRIATE EMISSION SYSTEM

HEAT RECOVERY VENTILATION SYSTEM

HEATING SYSTEM CONTROL

11

EEM

EXTERNAL WALL THERMAL INSULATION

WALL VS UNCONDITIONED THERMAL INSULATION

ROOF THERMAL INSULATION

FLOOR THERMAL INSULATION

WINDOW THERMAL INSULATION

Level of EEO

Cost of EEM

2 1

Level of EEO

Parameter values


RePublic_ZEB © 2016 of 13 21/12/2016

The common tool produces the following results:

Set of optimal Energy Efficiency Measures and relevant parameters (see Table 1);

Building primary energy use: renewable, non-renewable and total;

Renewable Energy Ratio (RER) for the considered building energy services;

Actualised global costs.

No. EEM

Energy Efficiency Measure EEM

Parameter Symbol

Before refurbishment

Cost-Optimal

Value Value No. EEO

1 External wall thermal insulation

Thermal transmittance Up 0.80 0.21 4

2 Wall vs unconditioned thermal insulation

Thermal transmittance Up,u 0.92 0.26 3

3 Roof/last floor thermal insulation

Thermal transmittance Ur 1.10 - -

4 Ground/first floor thermal insulation

Thermal transmittance Uf 0.73 0.28 2

5 Window thermal insulation

Thermal transmittance Uw 3.70

8

Generator for space heating and appropriate emission system

Generator efficiency (at design conditions)

ηgn,Pn,H 0.80 0.88 4

9 Generator for DHW

Generator efficiency (at design conditions)

ηgn,Pn,W 0.80

12 Thermal solar system

Surface of solar collectors

A 275 5

13 PV system Peak power Pp 45 5

15 Heating system control

Control efficiency ηctr 0.995 climatic+ ambient

Table 1. Example set of optimal Energy Efficiency Measures and parameters

2.3 nZEB SPECIFICATION AND CALCULATION

The tool investigates all the possible sets of technologies suitable for the nZEB retrofit of the building by testing each parameter level of the EEO, for each EEM, starting from the cost-optimal solution until the nZEB criteria are fulfilled. It produces graphs that compare the building in its existing state, the cost-optimal solution and the nZEB solutions in terms of global EP (renewable and non-renewable) and global cost. Respective examples of this are given in Figures 2a and 2b below.


RePublic_ZEB © 2016 of 13 21/12/2016

Figure 2a. Example energy performance comparison of the current state of a building and different retrofit solutions

Figure 2b. Example global cost comparison of the current state of a building and different retrofit solutions

3. CROSS-COUNTRY COMPARISON OF RESULTS The main report contains extensive tables and graphs that detail the performance and highlight the nZEB packages of measures for each reference building in each country.

Therefore the focus here is a cross-country comparison of the nZEB solutions in each partner country. Before proceeding though it should be noted that some inconsistencies arise from this comparison.


RePublic_ZEB © 2016 of 13 21/12/2016

Firstly, in some countries there is no official definition of nZEB. Therefore, most partners proposed retrofit solutions that accorded with the project definition of nZEB, i.e. a refurbished building that is more energy efficient than the cost-optimal solution, but at the same time is cost effective.

Other possible inconsistencies can also arise because some countries (e.g. Former Yugoslav Republic of Macedonia, Slovenia and Hungary) do not have official values for primary energy factors, specifically as regards the renewable fraction of primary energy. In these cases it was left to each partner to decide whether using the conversion factors as reported in ISO/FDIS 52000-1:2016, or whether using the factors already available at country level without specifying the renewable energy demand.

Further, the calculation assumes a continuous operation of the heating/cooling systems, according to the standard calculated rating approach. Therefore, the real energy consumption of buildings is generally lower (e.g. by about 30% in a school) than the standard energy performance. Thus, the energy performance, the global cost as well as the pay-back period here reported should be adjusted, especially in case of intermittent use of the heating system.

Finally, the energy performance depends significantly on the weather conditions, which may be different among the considered countries; thus, a comparison can be difficult.

Figure 3 shows the global total primary energy index subdivided into the non-renewable rate (in red) and the renewable rate (in green). It should be noted that nZEBs are generally characterized by a non-renewable primary energy of around 60 kWh/m2: some countries like Bulgaria, Hungary, Italy and Portugal achieve lower values, around 40 kWh/m2. Bulgarian nZEBs have the lowest energy intensity (less than 20 kWh/m2), while the most energy-intensive seems to be the Spanish, Greek and Slovenian nZEBs.

With regard to the non-renewable energy demand, it can be said:

Croatia and Spain have cases in which EPgl,nren is higher than 200 kWh/m2;

Former Yugoslav Republic of Macedonia, Greece, Hungary, Slovenia, Spain achieve values between 80 and 120 kWh/m2;

Croatia shows a wide spread of values, ranging from 8 to 118 kWh/m2.

For the total global energy performance index of the nZEB solutions, values are generally around 120 kWh/m2. Smart cases are those of the Bulgarian school and office, the Italian social housing and of the UK Victorian office. Conversely, Greece, Spain and Croatia, show higher values of EPgl,tot.

In terms of the RER, Figure 4 shows that most of the buildings achieve 50%, and in many cases the energy covered by renewables is around 80% (Bulgaria, Croatia and UK). At the other end of the scale, Spain in particular, but Croatia and Hungary too, achieve very low values of RER. It should be noted that the services considered in the RER calculation are not the same for all the countries: ventilation and in some cases lighting are not considered, as in Italy, Portugal, Hungary and Greece. Slovenia is a special case where the national law requires 25% share of RES in total final energy consumption to ensure the building’s systems function, so heat and electricity for ventilation, heating, cooling, hot water and lighting.


RePublic_ZEB © 2016 of 13 21/12/2016

* Not possible to calculate the renewable energy demand. Primary energy factors not available.

Figure 3. Non-renewable and renewable primary energy index of the nZEB solutions


RePublic_ZEB © 2016 of 13 21/12/2016

* Not possible to calculate the RER. Primary energy factors not available

Figure 4. RER (renewable energy ratio) of the nZEB solutions


RePublic_ZEB © 2016 of 13 21/12/2016

Figure 5 shows the differential global costs with reference to the existing building before refurbishment. Most of the solutions have a negative differential global cost, i.e. the retrofit solution is cost-effective in the 30-year period considered. The highest saving is that of the Italian school, which was a highly energy-intensive building before the retrofit; in this and other similar cases, the nZEB refurbishment leads to a very high energy saving and a significant energy cost reduction. The negative values of the differential global are generally between 100 and 200 €/m2; Slovenia achieves higher values. Positive values mean that the retrofit is not cost-effective, so the solution should not be considered. These cases are characterized by a high global cost that could mean that the building is not appropriate for an nZEB renovation, or that the technologies chosen for the retrofit save energy but are very expensive.

Figure 6 shows the actualized pay-back period associated with each retrofit. The actualized pay-back period – or discounted payback period - is calculated as the time to reach the break-even point, i.e. the point at which the sum of the discounted cash flows become positive from the income of the retrofit.

The black line refers to 30 years, i.e. the period set in the calculation process. Except for a handful of cases in Hungary and in Italy, the PBPact is always greater than 5 years; most of the cases are characterized by a PBPact of between 10 and 20 years.

Low pay-back periods relate to buildings that are energy-intensive before the refurbishment. In these cases the nZEB renovation gives good results, both from the economic and energy point of view. Again, it has to be remembered that these values refer to a continuous use of the building; this means pay-back periods for buildings characterized by intermittent use are generally higher than those calculated for the purposes of this cross-country comparison.

In conclusion, the results show that a retrofit towards the nearly zero energy target is technically feasible in most of the cases. The refurbishment leads to a high reduction of the non-renewable primary energy consumption and of the CO2 emission. Nevertheless, the costs of such retrofit measures are still too high to make the process economically attractive. For that reason, Deliverable D4.4 will focus on a sensitivity analysis aimed at highlighting the main economical parameters that influence the global cost. Results should provide suggestions and guidelines to authorities involved in the process of public building refurbishment.

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