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Sustainable Housing – The User Focus Johansson, Jan
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Johansson, J. (2013). Sustainable Housing – The User Focus. Paper præsenteret ved SB13 , Guimaraes, Portugal.
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Editors Luís Bragança
PORTUGAL SB13
CONTRIBUTION OF SUSTAINABLE BUILDING TO MEET EU 20-20-20 TARGETS
30 Oct > 1 Nov | 2013 | Guimarães | PORTUGAL
PORTUGAL SB13
CONTRIBUTION OF SUSTAINABLE
BUILDING TO MEET EU 20-20-20 TARGETS
Organized by
Universidade do Minho Instituto Superior Técnico
Partners
PORTUGAL SB13
CONTRIBUTION OF SUSTAINABLE
BUILDING TO MEET EU 20-20-20 TARGETS
Editors
Luís Bragança
Manuel Pinheiro
Ricardo Mateus
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any mean, without prior written permission from the Publisher.
ISBN 978-989-96543-7-2
Printed by Multicomp 1st edition, October 2013 Legal Dep. 365726/13
LEGAL NOTICE
The Publisher is not responsible for the use which might be made of the following information.
The international conference Portugal SB13 is organized by the University of Minho, the Technical University of Lisbon and the Portuguese Chapter of the International Initiative for a Sustainable Built Environment in Guimarães, Portugal, from the 30
thof October till the 1
stof November 2013.
This conference is included in the Sustainable Building Conference Series 2013-2014 (SB13-14) that are being organized all over the world. The event is supported by high prestige partners, such as the International Council for Research and Innovation in Building and Construction (CIB), the United Nations Environment Programme (UNEP), the International Federation of Consulting Engineers (FIDIC) and the International Initiative for a Sustainable Built Environment (iiSBE).
Portugal SB13 is focused on the theme “Sustainable Building Contribution to Achieve the European Union 20-20-20 Targets”. These targets, known as the “EU 20-20-20”
targets, set three key objectives for 2020:
•
A 20% reduction in EU greenhouse gas emissions from 1990 levels;
•
Raising the share of EU energy consumption produced from renewable resources to 20%;
•
A 20% improvement in the EU's energy efficiency.
Building sector uses about 40% of global energy, 25% of global water, 40% of global resources and emit approximately 1/3 of the global greenhouse gas emissions (the largest contributor). Residential and commercial buildings consume approximately 60%
of the world’s electricity. Existing buildings represent significant energy saving opportunities because their performance level is frequently far below the current efficiency potentials. Energy consumption in buildings can be reduced by 30 to 80%
using proven and commercially available technologies. Investment in building energy efficiency is accompanied by significant direct and indirect savings, which help offset incremental costs, providing a short return on investment period. Therefore, buildings offer the greatest potential for achieving significant greenhouse gas emission reductions, at least cost, in developed and developing countries.
On the other hand, there are many more issues related to the sustainability of the built environment than energy. The building sector is responsible for creating, modifying and improving the living environment of the humanity. Construction and buildings have considerable environmental impacts, consuming a significant proportion of limited resources of the planet including raw material, water, land and, of course, energy. The building sector is estimated to be worth 10% of global GDP (5.5 trillion EUR) and employs 111 million people. In developing countries, new sustainable construction opens enormous opportunities because of the population growth and the increasing prosperity, which stimulate the urbanization and the construction activities representing up to 40% of GDP. Therefore, building sustainably will result in healthier and more productive environments.
The sustainability of the built environment, the construction industry and the related activities are a pressing issue facing all stakeholders in order to promote the Sustainable Development.
The Portugal SB13 conference topics cover a wide range of up-to-date issues and the contributions received from the delegates reflect critical research and the best available practices in the Sustainable Building field. The issues presented include:
- Nearly Zero Energy Buildings - Policies for Sustainable Construction
- High Performance Sustainable Building Solutions
- Design and Technologies for Energy Efficiency
- Building Sustainability Assessment Tools - Renovation and Retrofitting
- Eco-Efficient Materials and Technologies - Urban Regeneration
- Design for Life Cycle and Reuse
- LCA of sustainable materials and technologies
All the articles selected for presentation at the conference and published in these Proceedings, went through a refereed review process and were evaluated by, at least, two reviewers.
The Organizers want to thank all the authors who have contributed with papers for publication in the proceedings and to all reviewers, whose efforts and hard work secured the high quality of all contributions to this conference.
A special gratitude is also addressed to Eng. José Amarílio Barbosa and to Eng.
Catarina Araújo that coordinated the Secretariat of the Conference.
Finally, Portugal SB13 wants to address a special thank to CIB, UNEP, FIDIC and iiSBE for their support and wish great success for all the other SB13 events that are taking place all over the world.
The Organizers
Luis Bragança – University of Minho
Manuel Pinheiro – IST - Tecnico of Lisbon University
Ricardo Mateus – iiSBE Portugal
Albert Cuchí
Universidad Politécnica Cataluña, Spain
Manuela Almeida
Universidade do Minho, Portugal Aleksander Panek
University of Warsaw, Poland
Maria Teresa Barbosa
Universidade Federal de Juiz de Fora, Brasil Alexander Passer
Graz University of Technology Austria
Marina Fumo
University of Naples, Italy Andreas Rietz
Fed. Inst. for Research on Building, Germany
Maristela Gomes da Silva University of Espirito Santo, Brasil António Tadeu
Universidade de Coimbra, Portugal
Mat Santamouris
University of Athens, Greece Appu Haapio
VTT, Finland
Miguel Amado
Universidade Nova de Lisboa, Portugal Charles Kibert
University of Florida, USA
Natalie Eßig
Hochschule München, Germany Christian Wetzel
Calcon, Germany
Nicolas Kerz
Fed. Inst. for Research on Building, Germany Dimitrios Bikas
University of Thessaloniki, Greece
Nils Larsson iiSBE, Canada Dorota Chwieduk
Institut Techniki Cieplenj, Poland
Pekka Huovila VTT, Finland Eduardo Maldonado
Universidade do Porto, Portugal
Petr Hajék
University of Prague, Czech Republic Emilio Mitre
GBC España, Spain
Raymond Cole
University of British Columbia, Canada Fátima Farinha
Universidade do Algarve, Portugal
Ricardo Mateus
Universidade do Minho, Portugal
Fernando Branco
Instituto Superior Técnico, Portugal
Rogério Amoêda
Green Lines Institue, Portugal Frank Schultmann
University of Karlsruhe, Germany
Ronal Rovers
Zuyd University, The Netherlands Gerd Hauser
Technical University of Munich, Germany
Said Jalali
Universidade do Minho, Portugal Helena Gervásio
Universidade de Coimbra, Portugal
Sungwoo Shin
Hanyang University, Korea Hipólito de Sousa
Universidade do Porto, Portugal
Tarja Häkkinen VTT, Finland Jaume Avellaneda
Universidad Politécnica Cataluña, Spain
Teresa Ponce Leão LNEG, Portugal Jorge de Brito
Instituto Superior Técnico, Portugal
Tomas Luetzkendorf
University of Karlsruhe, Germany Luís Bragança
Universidade do Minho, Portugal
Tom Woolley
University of Central Lancanshire, UK Luís Simões da Silva
Universidade de Coimbra, Portugal
Vanessa Gomes
Universidade Estadual de Campinas, Brasil Manuel Correia Guedes
Instituto Superior Técnico, Portugal
Vasco Peixoto Freitas Universidade do Porto, Portugal Manuel Duarte Pinheiro
Instituto Superior Técnico, Portugal
Vítor Ferreira
Universidade de Aveiro, Portugal
Foreword
Luís Bragança, Manuel Pinheiro, Ricardo Mateus
Chapter 1: Nearly Zero Energy Buildings
Cost optimal building renovation with a net zero energy target for the Portuguese
single-family building stock built before 1960 3
Manuela Almeida, Marco Ferreira, Micael Pereira
Zero-Energy-Buildings and their arrangement in Zero-Energy-Urban-Quarters in different climates: Derivation of design strategies based on climatic parameters, examples for building and urban quarter typologies and comparison with the existing
ones 11
Udo Dietrich, Franz Kiehl, Liana Stoica
The first phase of a zero emission concept for an office building in Norway 19 Torhildur Kristjansdottir, Sofie Mellegård, Tor Helge Dokka, Berit Time,
Matthias Haase, Jens Tønnesen
Assessing design practices towards nearly zero energy buildings 27 Patrícia Morais, Ana Tomé
Cost optimality and nZEB target in the renovation of Portuguese building stock.
Rainha Dona Leonor neighborhood case study 35
Manuela Almeida, Ana Rodrigues, Marco Ferreira
Energy Performance of a Galician Hostel 43
Ruth Dominguez Sanchez, César Bedoya Frutos
Monitoring of Indoor Climate of a Net Zero Energy Office in Flanders 51 Griet Verbeeck, Elke Meex
The qualifications and professional competencies of architects on the energy
efficiency of buildings. Are they prepared to embrace the 2020 targets? 59 Sílvia Fernandes, Rui Oliveira, Maria Isabel Abreu
Chapter 2: Policies for Sustainable Construction
Including sustainability into portfolio decisions: The example of the University of
Vienna 69
Sigrid Niemeier, Harald Peterka
Sara Amaral, Dulce Franco Henriques
Climate change effect on freeze-thaw cycles in Nordic climate 83 Toni Pakkala, Jukka Lahdensivu, Arto Köliö
Energy rating of windows for the cooling season: a proposal for Europe 91 Dimitrios Bikas, Katerina Tsikaloudaki, Konstantinos Laskos
A Qualitative Assessment of the UK Green Deal: Enabling Energy Efficiency of
Buildings by 2050 99
David Oloke
Dividing indoor comfort limits by climate zones and describing it as a curve for the
benefit of passive and low tech architecture design. 107
Gustavo Linhares de Siqueira, Udo Dietrich
The Primary Energy Factors Play a Central Role in European 2020 Targets
Achievement 113 Lorenzo Leoncini
Sustainability in construction, between politics and economics. A comparison of the
U.S. market and the Italian one. 121
Maria Antonia Barucco
Changing Mindsets; Identifying the Need for a Paradigm Shift in Construction
Education 129
Conor McManus, Garrett Keenaghan, Maurice Murphy
Tomorrow’s sustainability: Devising a Framework for Sustainability Education of
Future Engineers and Architects 137
Maria Olga Bernaldo, Gonzalo Fernandez-Sanchez, Ana Castillejo, Mª José Rodriguez-Largacha, Ana María Manzanero, Daniel Estévez, Maria Del Mar Cenalmor, Jesús Esteban
Chapter 3: High Performance Sustainable Building Solutions
Cost vs Benefits analysis in the implementation of sustainable construction principles
in a residential building 145
Sérgio Martinho, Constança Rigueiro, Ricardo Mateus
Water reuse for domestic consumption - A key element for environmental and
economic sustainability 153
José Coimbra, Manuela Almeida
Energy consumption and thermal comfort of a passive house built in Romania 161 Cristina Tanasa, Cristian Sabou, Daniel Dan, Valeriu Stoian
Post Occupancy Evaluation of University Eco Residences: A Case Study of Student
Accommodation at Lancaster, UK 167
Hasim Altan, Mohamed Refaee, Jitka Mohelnikova
Natural fibre reinforced earth and lime based mortars 183 César Cardoso, Rute Eires, Aires Camões
Rainwater Harvesting Systems in Buildings: Rapid Changes with Substantive
Improvements 191 Armando Silva Afonso, Carla Pimentel Rodrigues
The energy of water: An evaluation of direct electricity savings due to strategies of
water preservation in a social housing compound 199
Antonio Girardi
Comparison of costs of brick construction and concrete structure based on functional
units 207
Soheyl Sazedj, António J. Morais, Said Jalali
Sustainable Daylighting Design in Southern European Regions 213 António J. Santos
Moisture buffering and latent heat effects in natural fibre insulation materials 221 Neal Holcroft, Andy Shea
Potentialities of using PCM in residential buildings in Portugal 229 Olli Mustaparta, Sandra Silva, Dinis Leitão
Home automation controller for a water-flow window 237
Luis J. Claros Marfil, J. Francisco Padial Molina, Vicente Zetola Vargas, Graciela Ovando Vacarezza, Juan Miguel Lirola Pérez, Benito Lauret Aguirregabiria
Concept and International State of Building Commissioning Activitie’s 243 Filipe Silva, João Pedro Couto
Sustainable Social Housing - The User Focus 251
Jan Johansson
Tradition in Continuity: thermal monitoring in vernacular architecture of farmsteads
from northeast Portuguese region of Trás-os-Montes 259
Joana Gonçalves, Ricardo Mateus, Teresa Ferreira, Jorge Fernandes
The contribute of using vernacular materials and techniques for sustainable building 269 Jorge Fernandes, Ricardo Mateus, Luís Bragança
Chapter 4: Design and Technologies for Energy Efficiency
Urban Form and Daylighting: Examining daylighting conditions with regard to
building block typologies 279
Dimitra Tsirigoti, Katerina Tsikaloudaki, Dimitrios Bikas
combined with better quality and a more holistic building design Kevin Kelly, James Thomas Duff
Energy and water use patterns in Portuguese secondary schools – main relationships.
Seven school cases analysis. 295
Patricia Lourenço, Manuel Duarte Pinheiro, Teresa Heitor
Parametric analysis of the energy demand in buildings with Passive House Standard 303 Meri Cvetkovska, Andrej Andreev, Strahinja Trpevski, Milos Knezevic
Evaluating determinants of energy use in higher education buildings using artificial
neural networks – an enhanced study 311
David Hawkins, Dejan Mumovic
Energy efficiency of photovoltaic façade for different latitudes in Portugal 319 Helenice Maria Sacht, Luis Bragança, Manuela Almeida
Bioclimatic buildings strategies for the climate of Araras city, São Paulo - Brazil 327 Juliana Nascimento, Helenice Maria Sacht, Luis Bragança
Protocol of control for the model of building energetic efficiency in existing buildings 335 Ángel Rubio González
Towards adaptive control systems: Bayesian models for energy efficiency 339 Roberta Ansuini, Albero Giretti, Massimo Lemma, Roberto Larghetti
Sustainable Energy Management for Underground Stations: Potential Savings
through Lighting Upgrade 347
Roberta Ansuini, Albero Giretti, Massimo Lemma
Energy Assessment and Monitoring of Energy-Efficient House 355 Libor Šteffek, Petr Jelínek, Milan Ostrý
Chapter 5: Innovative Construction Systems
ECODOR: sustainable proportion for concrete sleeper 365
Maria Teresa Barbosa, Mariana Maia, José Castañon, Zelia Ludwig Technical solutions and industrialised construction systems for advanced sustainable
buildings 371
Eugenio Arbizzani, Paolo Civiero
A project contribution to the development of sustainable multi-storey timber
buildings 379
Catarina Silva, Jorge Branco, Paulo Lourenço
ARGAD: High Performance Mortar 387
Maria Teresa Barbosa, White Santos
Assessment and monitoring of a student residential building using an innovative
execution solution 403
Pedro Andrade, Safira Monteiro, Helena Gervásio, Milan Veljkovic
Chapter 6: Building Sustainability Assessment Tools
Space design quality and its importance to sustainable construction: the case of
hospital buildings 413
Maria de Fátima Castro, Ricardo Mateus, Luís Bragança
The Development of Building Materials Embodied Greenhouse gases Assessment System (SUSB-BEGAS) for Supporting the Green Building Certification System (G-
SEED) in Korea 421
Sungwoo Shin, Seungjun Roh, Sungho Tae
Can sustainability rating systems fairly assess construction solutions under
assessment? 427
Joana Andrade, Luís Bragança
Defining best practices in Sustainable Urban Regeneration projects 435 Guilherme Castanheira, Luís Bragança, Ricardo Mateus
An investigation of Indicators, Metrics, and Methods Used to Measure and Quantify
Green Buildings’ Occupancy and Usage 443
Mohamed Ouf, Mohamed Issa, Shauna Mallory-Hill
From lighthouse projects to sustainable building stock 451
Christian Wetzel, Rosemarie Dressel
Modelling Moisture and Site-Related Information for Sustainable Buildings 457 Christina Giarma, Dimitris Kotzinos
Comparison of two sustainable assessment tools on a passive office in Flanders 465 Elke Meex, Griet Verbeeck
Spatial Quality Assessments for Building Performance Tools in Energy Renovation 473 Fernanda Pacheco, Annemie Wyckmans
AQUA certification system and the design of buildings 481
Maria Aparecida Hippert, Luiz Felipe Dutra Caldeira
The implicit definition of ‘utility’ in the sustainable building assessment methods 489 Joan Puyo Collet, Albert Cuchí Burgos
A Review of Research Investigating Indoor Environmental Quality in Green
Buildings 497
Ahmed Radwan, Mohamed Issa, Shauna Mallory-Hill
Catarina Araújo, Luís Bragança, Manuela Almeida
Chapter 7: Renovation and Retrofitting
Renovation project / sustainable rehabilitation centre headquarters district of Porto -
Portugal. 515
Lurdes Duarte, Luís Narciso, Luis Calixto
Strategies for regeneration of widespread building heritage in Italy 523 Paola Piermattei
Environmental Impacts of Elementary School Building Renovation - Comparative
Studies 531
Jiri Sedlák, Zuzana Stránská, Karel Struhala, Petr Jelínek
Regenerative Universities? The role of Universities in Urban Regeneration Strategies 539 Duarte Marques Nunes, Ana Tomé, Manuel Duarte Pinheiro
The integration of sustainable solutions in Portuguese old building architecture 547 Rui Oliveira, Maria Isabel Abreu, Jorge Lopes
The Collective Self-Organized (CSO) housing approach: improving the quality of life
towards nearly zero energy strategies 555
Silvia Brunoro
Technologies, strategies and instruments for energy retrofitting of historic cities 565 Carola Clemente, Federica Cerroni, Paolo Civiero, Paola Piermattei, Mauro
Corsetti, Pietro Mencagli, Leonardo Giannini
The inhabitable greenhouse 573
Mathilde Petri, Mette Rasmussen
Criteria for thermal rehabilitation of hotels in Gran Canaria 581 Maria Eugenia Armas Cabrera, Jaume Avellaneda Diaz-Grande
Optimization of the sustainability during the refurbishment operation of a residential
building 589
Isabel Mateus, Ricardo Mateus, Sandra Monteiro da Silva
Thermal Rehabilitation for Higher Comfort Conditions and Energy Efficient
Buildings 597
Mihai Cinca, Olga Bancea
Energy efficient envelope for renovation of terraced housing 605 Andrea Boeri, Jacopo Gaspari, Danila Longo
Using MCDA to Select Refurbishment Solutions to Improve Buildings IEQ 615 Sandra Silva, Manuela Almeida
Which architecture has proven to be successfully climate responsive? Learning from traditional architecture by looking at strategies for resource efficient and climate
responsive constructions 623
Sonja Schelbach, Udo Dietrich
Research into natural bio-based insulation for mainstream construction 631 Ceri Loxton, Elie Mansour, Robert Elias
Bioclimatic solutions existing in vernacular architecture - rehabilitation techniques 639 Débora Ferreira, Eduarda Luso, Sílvia Fernandes, Jorge Vaz, Carlos
Moreno, Rafael Correia
Overview of Technological Industrialized Solutions for Temporary Facilities in
Construction Sites 647
Christine Miranda Dias, Sheyla Mara Baptista Serra
Chapter 9: Urban Regeneration
Science of complexity for sustainable and resilient urban transformation 659 Serge Salat
Sustainable tall building and vertical compact city 677
Sung Woo Shin
Solar urban planning to the EU 20-20-20 targets 697
Miguel Amado, Pedro Rodrigues, Francesca Poggi, João Freitas
Power of a Million Small 709
Pedro Faria
Urban Regeneration. Developing strong sustainable urban design perspectives 719 Duarte Marques Nunes, Ana Tomé, Manuel Duarte Pinheiro
Nearly zero energy applied to urban zones – Main Challenges and Perspectives 727 Giorgio Borlin, Manuel Duarte Pinheiro, Maria Beatriz Marques Condessa
ICT supporting energy efficiency improvements in urban and rural neighbourhoods 735 Mari Sepponen, Martine Tommis
Monitoring and Evaluation of urban regeneration processes. The case of Cova da
Moura. 743
Ana Valente
How to address sustainability at the city level 751
José Amarilio Barbosa, Luís Bragança, Ricardo Mateus
Building connections and Material recovery: from deductive to inductive approach 763 Claudia Escaleira, Rogério Amoêda, Paulo Cruz
Against Over-materialization. Architecture of Negatonnes 771
Leszek Świątek
Opportunities and obstacles of implementing transformable architecture 775 Mieke Vandenbroucke, Wim Debacker, Niels De Temmerman, Anne Paduart
Multiple design approaches to transformable building: construction typologies 783 Waldo Galle, Niels De Temmerman
Condition monitoring and durability assessment of straw bale construction 791 Andrew Thomson, Pete Walker
Innovative Sustainable Architecture: constructive processes and materials 799 Mariana Pinto, Pedro Henriques
Chapter 11: LCA of sustainable materials and technologies
Carbon footprint impact of balcony glazing in Nordic climate 809 Kimmo Hilliaho, Jukka Lahdensivu
Assessment of carbon footprint of laminated veneer lumber elements in a six story
housing – comparison to a steel and concrete solution 817
Lars Gunnar F. Tellnes, Torhildur Fjola Kristjansdottir, Magnus Kron, Sigurd Eide
Designing Model House Based on the Cradle-To-Cradle Methodology 825 Inês Ramalhete, Miguel Amado
LCA “from cradle-to-cradle” of energy-related building assemblies: Promoting eco-
efficient materials 837
José Dinis Silvestre, Jorge de Brito, Manuel Duarte Pinheiro
Reducing fossil based energy consumption and CO2 emissions in the construction
sector 847
Pedro Henriques, Álvaro Pereira
Life Cycle Assessment of an ETICS system composed of a natural insulation
material: a case study of a system using an insulation cork board (ICB) 855 Marta Matos, Liliana Soares, Luis Silva, Pedro Sequeira, Joaquim Carvalho
Energy Performance Certificate: A valuable tools for buiding-to.grid interaction? 865 Marta Oliveira Panão, Hélder Gonçalves
Smart battery management systems: towards an efficient integration of Electrical
Energy Storage Systems in Smart Regions 871
António Gano, Hugo Silva, João Correia, Maria Martins The NetZEBs in the near Future. Overview of definitions and guidelines
towardsexisting plans for increasing nZEBs 879
Laura Aelenei, Hélder Gonçalves, Daniel Aelenei
Nudging Residential Consumers to Save and/or Defer Energy Consumption 887 Lucy Ting, Hélder Leite, Luís Barreira
Enabling Self-Healing Strategies in a Smart Grid Context 893
Hélder Leite, Luís Moreira, Nuno Silva
Value materials and energy flow to toward energy independence: agro-forest and
urban biorefineries 897
João Nunes
Chapter 1
Nearly Zero Energy Buildings
1 INTRODUCTION
Climate change observed on the planet is taking an increasingly important role on the society, thus requiring an urgent response at global level (European Commission, 2006).
Since buildings account for about 40% of energy consumption in the European Union, this sector has become an important target for interventions to reduce the greenhouse gases that are released into the atmosphere (European Commission, 2012a).
Within this context, the concept of nearly zero energy buildings arose in the European ener- gy policy as a tool to deal with the need of independence from fossil energy sources and exter- nal energy supply (European Parliament, 2010). Energy efficiency and energy harvesting from renewable sources on site or nearby are the essential elements that from the year 2020 on will allow that all new buildings will be nearly zero energy buildings (NAIMA, 2011). However, the long term goals of reducing energy consumption in the European Union for the year 2050 (Eu- ropean Commission, 2011) are impossible to achieve without interventions on the building stock given the very low rate of replacement of the existing buildings by new ones.
The recast of the Energy Performance of Buildings Directive (European Parliament, 2010), besides the definition of Nearly-Zero Energy Buildings, introduced the concept of Cost Optim- al levels, which will pave the way of the new energy codes in all EU Member States and their building sector. The concept of Cost Optimal levels is intended to guide Member States on es- tablishing minimum energy performance requirements based on the costs during the entire building life cycle (European Commission, 2012a, 2012b) as opposed to just consider the initial investment cost.
In this context, this paper aims at analyzing the most cost-effective packages of renovation
Cost optimal building renovation with a net zero energy target for the Portuguese single-family building stock built before 1960
Manuela Almeida
University of Minho, Civil Engineering Department, Guimarães, Portugal malmeida@civil.uminho.pt
Marco Ferreira
University of Minho, Civil Engineering Department, Guimarães, Portugal marcoferreira@civil.uminho.pt
Micael Pereira
University of Minho, Civil Engineering Department, Guimarães, Portugal a54248@alunos.uminho.pt
ABSTRACT: Cost Optimality and nearly Zero Energy Buildings (nZEB) are two fundamental concepts within the current European Union policy related to the energy performance of build- ings and consequently related to climate change mitigation and non-renewable resources con- sumption. While Cost Optimality is mainly focused on costs, nZEB are focused on low energy consumption levels and on site renewables harvesting.
If the differences between Cost Optimality and nZEB approaches result in major differences in the selection of the best package of renovation measures, the transition from the Cost Optimal concept to nZEB might result incompatible. In this context, using a virtual building representing the Portuguese residential building stock from the 20th century prior to 1960, this study investi- gates the most cost-effective packages of renovation measures to achieve a zero energy balance building and compares these packages with those resulting from the calculation of cost-optimal levels.
Investigating the trade-offs between a renovation towards zero energy balance and a cost optim- al renovation without the use of renewables is relevant to achieve a smooth transition from Cost Optimal levels to nearly Zero Energy Buildings.
measures to achieve a zero energy balance building and compare these packages with those re- sulting from the calculation of cost-optimal levels for a typical building representative of the Portuguese housing stock built before 1960. Investigation of the trade-offs between a renovation towards zero energy balance and a cost optimal renovation without the use of renewables is re- levant to achieve a smooth transition from Cost Optimal levels to nearly Zero Energy Buildings.
2 METHODOLOGY FOR THE CALCULATION OF COST OPTIMAL LEVELS
The economic viability of a building renovation towards a zero energy balance (for heating, cooling and domestic hot water (DHW) preparation) was determined according to the cost op- timal methodology presented by the European Union (European Commission, 2012a).
In order to obtain the cost optimal level for a building renovation it is necessary to test dif- ferent packages of renovation measures to improve the energy performance of the building and calculate the associated energy needs, the costs to implement those measures and the running costs during the remaining life span of the building.
These packages of measures should be chosen considering that measures applied in a given building element or system can affect the energy performance of other systems. This happens for example when considering different levels of insulation, for which higher insulation means lower heating needs and thus smaller heating devices.
Once defined and calculated the results for each renovation package, it is possible to build a graph based on the use of primary energy and the overall costs associated with the various ener- gy efficiency measures. In this graph a costs curve is created, with the lower points of the curve indicating the packages of measures with the lowest global costs considering the investment costs and the running costs over the entire building life cycle, as demonstrated in Figure 1.
Figure 1 – Cost optimality
Then, with the final goal of obtaining variants of the building with zero energy balance, meas- ures for the use of renewable energy sources are tested. The primary energy use of each variant is balanced with renewable energy and thus allowing to calculate and compare the overall costs associated with each renovation package in order to get the lowest global cost over the building lifecycle.
3 THE CASE STUDY
The building under analysis is representative of the Portuguese residential building stock from a period where energy efficiency was not a concern.
Different efficiency measures in the building envelope and different systems for HVAC and DWH were tested, evolving the building to better energy performance levels and subsequently introducing on-site renewable energy systems (RES).
3.1. Characterization of the reference building
The object of this study is a virtual building that represents the Portuguese existing buildings from the 20th century built before 1960. This building was created based on the data available in the database of the Energy and Indoor Air Quality in Buildings National Certification System (SCE), namely on the dimensions and geometry, construction materials and HVAC and DHW systems. For the location it was assumed the district of Braga, more specifically Guimarães at an altitude of 200 meters.
The selection of the most frequent characteristics of the buildings from this period led to a virtual building that is a single family house with 3 bedrooms consisting of a basement and a ground floor with 80m2 and floor to ceiling height of 2.7m. Typically the building has lightweight slabs; non-heated attic covered by a wooden roof with ceramic tiles, 50cm thick stone masonry walls with plaster on both sides and windows with wooden frames and single glazing.
The building presents four facades, N, S, E and W oriented, having an average width of 8.94m2 per facade, a total area of facades of 96.55 m2 and a total area of glazing of 12m2, which represents about 12% of the building envelope.
Usually these buildings do not have any insulation, and make use of some simple systems for heating, cooling and preparing hot water. Commonly for DHW preparation a gas water heater is used and electric appliances as fans and electric heaters are used for cooling and heating. Thus, the building presents annual nominal global needs of primary energy in the range of 712kWh/m2.y to fulfill all the energy needs of the building for heating, cooling and DHW. For this study, the energy needs were calculated following the Portuguese thermal code methodolo- gy (Portugal, 2006) and the primary energy use was calculated considering the total energy needs and conversion factors of 2.5kWhPE/m2.y per kWh/m2.y for electricity and 1kWhPE/m2.y per kWh/m2.y for gas.
3.2. Identification of different energy efficiency measures
The measures tested were current renovation measures in the Portuguese market that are tar- geted to improve buildings energy efficiency. Thus, 96 different packages of measures were created by changing various factors such as insulation levels and window types, which were combined with six different HVAC and DHW systems.
At the level of the building envelope, various measures that increased the level of thermal in- sulation were tested. Outer walls measures are based on the application of ETICS system with a polystyrene (EPS) layer with thicknesses that vary from 30mm up to 140mm.
For the roof, it was considered the application of an insulation layer over the slab. The insu- lation material considered was extruded polystyrene (XPS) and polyisocyanurate (PIR ) with various thicknesses (XPS varying from 30 up to 160mm and PIR varying from 80 up to 140mm).
In the basement ceiling, insulation measures included XPS with dimensions varying between 30 to 160mm and PIR varying from 30 to 80mm.
Regarding the windows, new PVC window frames with double glazing and thermal trans- mission coefficient of 2.00 W/m°C were taken into consideration.
In each package of measures different systems for HVAC and DHW with different efficien- cy and energy sources were used, such as two heat pumps, one with COP 4.1 and EER 4.0 and another with COP 3.33 and EER 2.68, both for heating, cooling and DHW. Other solutions in- cluded HVAC with COP 4.10 and EER 3.50, gas water heater with an efficiency of 86% and an electric water heater with efficiency of 80% both for DHW and a gas boiler with efficiency of 93% for heating and DHW.
Regarding on-site RES, three solutions were tested, namely a biomass boiler with efficiency of 92%, solar thermal collectors and photovoltaic panels for electricity generation.
3.3. Calculation of the global costs
The calculation of the investment costs was done based on a database with the true market val- ues and thus obtaining prices that were comparable with the currently in practice by Portuguese
companies. This database is provided by CYPE, SA (http://www.geradordeprecos.info/) and al- lows obtaining construction costs taking into account the values of all materials as well as the costs associated with installation, removal and maintenance.
Regarding the costs of energy and carbon emissions, the values published by the European Union (http://ec.europa.I/energy/observatory/trends2030/indexen.htm) and the 2010 scenario of the International Energy Agency for the gas were assumed (http://www.worldenergyoutlook.org/publications/weo-2010/). For the costs associated with the price of pellets for the biomass boiler, it was considered the current market price with a future increase of 3% per year. Table 1 presents the costs associated with each source of energy and the production of CO2 used throughout this study.
Table 1 – Energy and carbon emissions costs
Energy prices (without and with taxes)
and CO2
2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043
Electricity (€ cents per
kWh)
21 21 22 22 23 23 24 24 24 25 25 25 26 26 26 26 26 26 26 26 26 26 25 25 25 25 25 24 24 24 24 Gas
(€ cents per kWh)
7 8 8 8 9 9 9 9 9 10 10 10 10 10 10 10 10 11 11 11 11 11 11 11 11 11 11 11 11 11 11 CO2
(€ per ton.) 20 20 20 20 20 20 20 20 20 20 20 20 20 35 35 35 35 35 50 50 50 50 50 50 50 50 50 50 50 50 50
For the calculation of the overall costs associated with each variant, a discount rate of 6%
was used, as suggested by the European Commission (European Commission, 2012a).
3.4. Cost optimal calculations
Analyzing the different renovation packages, those with the lowest global costs within each group of building systems for heating, cooling and DHW preparation have been identified.
Figure 2 shows the global costs and the non-renewable primary energy associated to each reno- vation package. In Figure 2, each mark represents a different renovation package.
Figure 2 demonstrates that the package of measures with the lowest global costs is associated with the use of a gas boiler for heating and DHW preparation. Although these packages of measures, as well as those with the biomass boiler are not able to provide cooling, the introduc- tion of an equipment only to deal with cooling needs is not usual in residential Portuguese buildings and the low cooling needs that are experienced in most of the country makes such an investment generally unjustified.
Considering the package of measures with systems that also deal with active cooling, the lowest costs are found with the use of a multi-split HVAC system for heating and cooling and a gas heater for DHW preparation. The use of heat pumps lead to low non-renewable primary energy use, but their initial costs compromise their economic performance even considering the entire life cycle of the building. However, attention should be paid to the fact that the two most cost effective packages of systems for HVAC and DHW require the availability of the natural gas grid, which doesn’t cover all areas of the country. If natural gas is not available, the pack- ages of measures using the multi-split HVAC system combined with electric heater for DHW, the biomass boiler and the heat pump with COP 4.1 and EER 4.0, all present very similar global costs with huge differences in the non-renewable primary energy use (128kWhm2.a for the HVAC, 56kWhm2.a for the heat pump, and 0kWh/m2.a for the biomass boiler).
Figure 2 – Cost optimality evaluation without costs or energy restrictions
3.4. Impact of renewables on the cost effectiveness of HVAC and DHW systems
After this analysis, the use of on-site RES has been tested, with the introduction of a solar ther- mal system to reduce the energy needs to prepare DHW and photovoltaic panels to generate electricity in a quantity that equals the non-renewable primary energy use and thus, transform- ing the renovated building into a building with a zero non-renewable primary energy use for heating, cooling (when provided) and DHW preparation.
The contribution of the thermal solar system was calculated with the SOLTERM 5.0 soft- ware and the calculation of the photovoltaic power (kWp) required to generate the needed elec- tricity was calculated using the online tool PVGIS (http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php #), made available by the European Union, which takes into consideration factors such as the orientation of the photovoltaic panels, the slope and the location.
In Figure 3, the various packages of measures with a zero non-renewable primary energy use are presented associated to their global costs. Figures 2 and 3 shows that the hierarchy of cost effectiveness from the several HVAC and DHW systems didn’t suffer major modifications with the use of on-site RES. Only for the two solutions using multi-split HVAC for heating and cool- ing a relevant approximation happens. In fact, with on-site RES, the use of an electric heater or a gas heater for DHW becomes almost equivalent, certainly due to the significant reduction of energy needed to increase the water temperature by the effect of the solar thermal system.
Again with the exception of the strong effect in the DHW system using an electric heater, al- so the differences in global costs between the several HVAC and DHW systems are similar with those obtained in the analysis without on-site RES.
Considering these results it is possible to conclude that the installation of on-site RES doesn´t change significantly the hierarchy of cost effectiveness between the different HVAC and DHW systems.
Figure 3 – Cost optimality evaluation towards zero non-renewable primary energy use
3.5. Impact of renewables on the cost effectiveness of envelope elements
The impact of on-site RES on the cost effectiveness of measures on the building envelope has also been tested.
Figure 4 presents all packages of measures to improve the building envelope in which the gas boiler has been used for heating and DHW preparation. Each mark represents a building renova- tion variant (VAR) with its non-renewable primary energy use and global costs.
Figure 4 – Cost optimality evaluation with the use of gas boiler for heating and DHW preparation
The cost optimal package of measures, identified as VAR 21.I, includes ETICS in the outer walls with a 100mm thick layer of EPS; a 140mm thick layer of PIR on the ceiling; a 50 mm thick layer of PIR in the basement ceiling; and PVC frames with double glazing in windows.
After the introduction of thermal solar and photovoltaic panels to obtain a zero non- renewable primary energy balance, the package of measures leading to the optimal cost is a slightly more efficient one, as can be seen in Figure 5. In this case, the package of measures with the lowest global cost is identified in Figure 5 as VAR 21.IV - ER and includes ETICS in the outer walls with a 120mm thick layer of EPS; a140mm thick layer of PIR on the ceiling slab; a 50mm thick layer of PIR in the basement ceiling; and PVC frames with double glazing in windows.
The package of measures with the lowest global cost, when the goal is zero non-renewable primary energy balance, presents a level of insulation in the exterior facade slightly above the value of the renovation package that led to the optimal cost without the zero energy target. This package, due to the high investment costs in on-site RES, has an associated global cost of ap- proximately €10,800 higher than the cost optimal package without renewables, which means an increase of nearly 30% of the global costs and an increase of nearly 50% in the investment costs.
Figure 5 – Cost optimality evaluation with zero non-renewable primary energy use with the use of gas boiler for heating and DHW preparation
Analyzing the other systems for HVAC and DHW, the variations are very similar to the ones presented for the gas boiler. In the case of the multi-split HVAC with the electric heater for DHW and also in the case of the biomass boiler for heating and DHW, a change in the package of measures with the lowest global cost occurs for a package of measures with a slightly better energy performance. In the case of the heat pumps and also in the case of the multi-split HVAC with a gas heater for DHW, the cost optimal package is also the package with the lowest global cost in the evaluation for zero non-renewable primary energy use.
Considering these results it is possible to conclude that the installation of on-site RES doesn´t change significantly the hierarchy of cost effectiveness between the different packages of measures in the building envelope. Nevertheless, there is a clear tendency for the reduction of the gap in global costs between the cost optimal package of measures and those with better energy performance and in some cases the lowest global costs are obtained with packages with slightly better energy performance.
4 CONCLUSIONS
The results presented in this article are part of a broader ongoing work that will consider single- family buildings from different periods and in different locations in Portugal. Although actual results are only referring to a single building type and location, they already allow drawing
some conclusions concerning the cost effectiveness of the combination of measures to improve the energy performance of the building envelope and of the HVAC and DHW systems and the use of on-site harvested renewable energy to achieve a zero energy balance.
Without the restriction of zero energy balance, the cost optimality is found for packages of measures using natural gas, if only for DHW or also for heating. If natural gas grid is not avail- able, the packages of measures using a multi-split HVAC system combined with electric heater for DHW, the biomass boiler or the heat pump, all present very similar global costs with signifi- cant differences in the non-renewable primary energy use. In these cases of similar global costs, the building variants with the lowest non-renewable primary energy should be chosen.
With the introduction of a solar thermal system to reduce the DHW energy needs and photo- voltaic panels to generate electricity in a quantity that equals the non-renewable primary energy use, the hierarchy of cost effectiveness from the several used HVAC and DHW systems, didn’t suffer major modifications. An exception has been observed in the synergy with the packages of measures using an electric heater for DHW, certainly due to the significant reduction of the energy needed to increase the water temperature by the effect of the solar thermal system, re- ducing the impact of the use of a low efficient system such as the electric DHW heater.
Considering the impact of the use of on-site RES on the cost effectiveness of the measures in the building envelope, it is possible to conclude that although their use doesn´t change signifi- cantly the hierarchy of cost effectiveness between the different packages of measures, there is a tendency for the reduction of the gap in global costs between the cost optimal package of meas- ures and those with better energy performance. In some cases the lowest global costs are ob- tained with packages with slightly better energy performance than the cost optimal package without a zero energy restriction.
The actual results, which are to be confirmed with studies on other buildings from different periods and located in other parts of the country, point out to a robustness of the cost optimal methodology in the definition of the most cost effective packages of measures in the building envelope, with very similar results for a zero non-renewable primary energy goal or without this restriction. Nevertheless, a cost optimal range instead of a cost optimal single package should be considered, once some combinations of HVAC and DHW systems and on-site RES, shift the cost optimal envelope package to a different one with slightly better energy performance.
Complementary, these results also point out to synergies between the use of on-site RES and the DHW systems, allowing the choice of simpler equipments with a lower investment cost and reducing the impact of the use of electricity as the energy vector in the quantification of the non- renewable primary energy.
REFERENCES
European Commission 2006. The European Climate Change Programme. European Communities. ISBN 92-79-00411-5.
European Commission 2011. A Roadmap for moving to a competitive low carbon economy in 2050.
European Commission 2012a. Commission Delegated Regulation (EU) No 244/2012 of 16 January 2012 supplementing Directive 2010/31/EU of European Parliament and of the Council on the energy per- formance of buildings by establishing a comparative methodology framework for calculating cost- optimal levels of minimum energy performance requirements for buildings and building elements.
Official Journal of the European Union L81/18.
European Commission 2012b. Guidelines accompanying the Commission Delegated Regulation (EU) Nº244/2012 of 16 January 2012, supplementing Directive 2010/31/EU of the European Parliament and of the Council on the energy performance of buildings. Official Journal of the European Union C115/1.
European Parliament and the Council of the European Parliament 2010. DIRECTIVE 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings (re- cast). Official Journal of the European Union.
NAIMA - North American Insulation Manufacturers Association 2011. Zero and Net-Zero Energy Build- ings + Homes
Portugal 2006. Thermal Performance Building Regulation (RCCTE). Diário da República, Decreto-Lei n.º 80/2006.
1 INTRODUCTION
In the European Union, the building sector is responsible for 40% of the primary energy demand.
Thus, a notable reduction could be achieved by energetically optimising the building stock, espe- cially in the context of zero-energy standard being pursued. According to the Energy Performance of Buildings Directive (EPBD) 2010/31/EU, new and retrofitted nearly-Zero-Energy-Buildings should be reached by 2020, setting minimum requirements for both the envelope and the technical systems (EPBD, 2010). In a Zero-Energy-Building (ZEB) 100% of the consumed primary en- ergy has to come from renewable energy sources. As claimed by the directive, these renewable energy sources have to be gained on site, e.g. on the building’s façades / roof and/or in the es- tate’s ground. Weaker ZEB definitions allow compensation measures to balance energies: trans- fer of renewable energy sources produced off site or co-generation etc.
Up to now, two different concepts of energetically optimised buildings exist. A passive method where the building’s energy demand is minimised by passive measures (“Passive House”) and an active approach where solar panels and similar technical measures are used to cover the energy demand (“Solar House”). The application of only one of these principles is not sufficient to reach a ZEB.
A well-designed synthesis of both is necessary, following the sequence: reducing the build- ing’s primary energy demand to its minimum with design strategies, covering the remaining
Zero-Energy-Urban-Quarters in different climates: Derivation and application of design strategies based on climatic parameters.
Udo Dietrich
HafenCity Universtät Hamburg, REAP Research Group, Hamburg, Germany udo.dietrich@hcu-hamburg.de
Franz Kiehl
HafenCity Universtät Hamburg, REAP Research Group, Hamburg, Germany franz.kiehl@hcu-hamburg.de
Liana Stoica
HafenCity Universtät Hamburg, REAP Research Group, Hamburg, Germany liana.stoica@hcu-hamburg.de
ABSTRACT: In a Zero-Energy Building, the primary energy demand for heating, cooling, ven- tilation, hot water and artificial light should be reduced to zero. To reach this goal, buildings have to be optimised energetically. Nevertheless, some energy demand will always remain and has to be covered by renewable energy sources gained on site (photovoltaic, geothermal etc.).
The resulting competition between the area of use (producing energy demand) and the area of the roof / the building envelope and the size of the building estate leads to limitations in the ur- ban design. First of all, the maximum number of storeys for the single building and secondly – to avoid shading – the minimum distances to neighbouring buildings have been investigated here. In a student course, optimised standard office rooms for 15 different locations with 15 dif- ferent climatic conditions have been developed. Their energy demand has been simulated and compared with climatic parameters such as heating and cooling degree hours and a good corre- lation between them could be proven. The resulting linear correlation equations may serve as a tool for the assessment of the energy demand of energetically optimized buildings, based only on climatic parameters – which can be especially important before the first design step. The ap- plication of this tool to Porto and Hamburg leads to different proposals for optimised buildings and their arrangement in an urban situation. While in Hamburg a satisfying urban density can be reached only with compensation measures for heating and power, the situation in Porto allows for buildings with up to 7 storeys and a high urban density.
primary energy demand with renewable energy gained on site and use compensation measures to bring the balance to zero. For some locations in the world, it is possible to cover the primary energy demand on site, for others not. The first two points create a further competition between the façade’s transparent areas (for optimal daylight supply and minimal power demand for arti- ficial light) and opaque areas (for solar panels to gain renewable energy). Furthermore, the whole building shape will become an important passive measure to optimise energy demand and production. The architect is in charge of an optimised building shape, which can be applied at an early design stage.
As solar radiation should have access to façades and roof surface, distance and placement of buildings in an urban situation represent a core aspect. Therefore, an integrated energy concept starts with urban planning and not just on the building level.
Different locations have diverse needs and preconditions, leading to different design rules and architectural solutions for zero-energy urban quarters and buildings in different climates.
Such a design approach is climate responsive and should lead to a new culture of climate- responsive architecture.
2 METHODOLOGY
The M.Sc. Degree Programme “Resource Efficiency in Architecture and Planning” (REAP, 2012) at the HafenCity University Hamburg emphasises holistic design for sustainable urban development projects, including scientific approaches of water, material and energy concepts. In this context, the course “Climate-responsive Architecture and Urban Planning” encourages the students to apply their knowledge of building physics to buildings around the world. With the task of adapting buildings to the conditions of local climate and optimising indoor comfort, stu- dents are required to investigate their own case study. Passive and active measures should be applied as far as possible. The overall aim of the course is to find out if and how far it is possi- ble to realise ZEBs in all parts of the world; a detailed description of the course can be found in (Dietrich, Kiehl, Stoica, 2013).
For the course, 15 different locations in different latitudes were preselected: Reykjavik, Oslo, Hamburg, Chicago, Beijing, Cairo, Delhi, Mexico City, Santo Domingo, Addis Ababa, Singa- pore, Dar Es Salaam, Jakarta, Sydney, Santiago de Chile. For this paper the location Porto was supplementary regarded on the basis of the prognosis tool described in chapter 6.
Figure 1. International style office room.
To simplify the task and to be comparable between all student groups / locations, it was pre- determined to deal with a standard office room for 12 users (area of usage 168 m²). It was as- sumed that this room could be one of a series of rooms, situated in the middle of an office build- ing so that the building continues horizontally and vertically.
As a starting point “before optimisation”, an “international style” standard room was defined.
This room has two fully glazed façades, an internal shading system, light construction, air con- ditioning (26°C) and artificial light and is operating during the whole time of use (7am to 6 pm).
The room has been simulated with a self-developed interface on energy plus (Primero-Comfort, Primero 2013) in advance for all the locations, data of the energy demand for heating, cooling, artificial light and ventilation was given to the students.
Based on these data, each student group had to estimate the maximum number of storeys and the minimum distance of neighbouring buildings to reach a ZEB with international style rooms in one of the given locations. Therefore they had to deal with the façade / roof areas as collector surface and/or the estate area for geothermal systems in their first presentation.
The second presentation included an analysis of vernacular and best practice architecture in the given locations as well as the location’s climate and the derivation of design strategies.
Based on this knowledge, students should optimise the international standard office room ac- cording to the local conditions. The subjects covered in the final presentation included the esti- mation of the maximum number of storeys and the minimum building distances to reach a ZEB.
The rooms had to be optimised, so that collecting surfaces and/or the estate area could be used to cover the energy demand with renewable energy sources. First rules for regulations in cli- mate-responsive urban planning were derived from this.
In order to develop the final design and urban situation of the climate-adaptive building, it was necessary to have information about the energy demand of this optimised room as a starting point. One possibility for them was to simulate the proposed optimised room during the course.
Although this is possible, experience shows that these simulations are often too complex and time consuming, distracting students from the main target of the course. For this reason, another method has been developed to avoid these simulations. The results of the first cycle of our course were a row of optimised rooms for different locations. These rooms have been simulated and a comparison of the resulting energy demand with other typical data for the same location, like heating or cooling degree hours, and found a very good correlation between them.
Based on these correlations, the student groups have been offered an estimated energy de- mand for optimised rooms in their location. The results are accurate enough for the main target of the course and help to avoid the execution of further detailed simulations.
The energy concept that should be applied in all case studies is based on a combination of geothermal heating and cooling and solar energy (PV modules) for the generation of electricity.
The geothermal system consists of borehole heat exchangers in the ground, coupled with an electrically driven heat pump. The boreholes are assumed to have a depth of 100 meters, using the ground as a heat source in winter and as a heat sink in summer. Each borehole needs to be placed a specific distance away from the next one. For this distance, 10 % of their length has been suggested, leading to the rule of thumb: one meter of borehole needs 1 m² of estate. One meter of a borehole is able to deliver 600 Wh of thermal energy per day (Zimmermann, 1999).
The size of the geothermal system is determined by the maximum daily heating or cooling en- ergy. For the heat pump, a coefficient of performance (COP) of 2.5 was assumed for cooling and 3.5 for heating. Geothermal systems are being used more and more around the world, espe- cially in combination with optimised buildings. Thus, they seem to have a big future.
The power demand of the heat pump, artificial light and mechanical ventilation has to be covered by PV modules, which can be installed on either the building’s roof or façades. In case PV modules are installed on pitched roofs or façades, buildings need a minimum distance to avoid one building from shading the next. For power, a primary energy factor of 3 has been used for all calculations.
If it is not possible to meet the target, using only on-site renewable energy in an urban sce- nario, compensation measures have to be proposed.
3 ADAPTIVE, HYBRID OR AIR-CONDITIONED?
An adaptive building is understood as a building where the users can adapt their surrounding according to their preferences: Operable windows, personal switches for artificial light, me- chanical ventilation, thermostats etc. If users are allowed to adapt themselves to (higher) indoor temperatures during hot periods by changing their clothes (no or weakened dress code!), inves- tigations show that users may feel well in remarkably higher temperatures than in non-adaptive surroundings (air-conditioned buildings).
Adaptive comfort models such as (EN 15251 2007) differ between naturally ventilated (adap- tive) and air-conditioned (non-adaptive) buildings. For both building classes EN 15251 distin- guishes three comfort classes: 1- high standard (for special uses like hospitals), 2 - good stan- dard (for all new buildings), 3 - low standard (acceptable for refurbished buildings). The
relevant comfort belt may be exceeded during a limited part (3 or 5%) of the hours of use. For an office, this means that about 100 hours per year are allowed to exceed the comfort belt.
In air-conditioned buildings, the user expects a constant temperature (mostly 26°C) inde- pendent of the outdoor situation. In adaptive buildings, the expected temperature varies slightly with the mean value of outdoor temperature.
Figure 2. Comfort diagram according to the scheme of EN 15251 (left) and with comfort belts according to EN 15251 (right), assessment of outdoor temperature in Delhi.
Figure 2 illustrates this situation. Left, the comfort belts for the three comfort classes are marked. The indoor temperatures are normally displayed as points in this EN 15251 scheme to assess indoor climate. In this diagram however, the points represent outdoor temperatures.
Given the fact that for real air changes, indoor temperatures remain a few degrees below out- door temperatures for heavy construction – or are almost equal to outdoor temperatures for light construction, an adaptive comfort model such as EN 15251 provides a good tool for pre- assessing, if there is a chance for reaching comfort during hot periods with passive measures (natural ventilation). As an example, Figure 2 (left) shows a lot of points for Delhi, which are both below and above the upper comfort limit – the number of points exceeding the comfort level makes up much more than 3%. To conclude however, that comfort can’t be reached in an adaptive building but only in an air-conditioned one would be premature. If the x-axis of the EN 15251 scheme is changed into the real-time axis, a different picture can be shown (Figure 2, right). Now it can be seen, that the upper line of the comfort belt is not exceeded during most of the months, so that an adaptive building is possible here. Only during the hottest months, an air conditioned building is necessary. Summing up the findings so far, a hybrid building can be suggested, operating for 5 months in an adaptive way (saving a lot of energy for the mechanical ventilation and cooling system) and 7 months with air conditioning.
Comfort class 2 can be reached with adaptive building concepts during the whole year in Reykjavik, Oslo, Hamburg, Mexico-City, Addis Ababa and Sydney. If users in hot climates are adapted to it and would accept higher temperatures than assumed in EN 15251, the upper line of the comfort belt can be shifted upwards. Then, comfort class 2 can be reached in Singapore, Santiago de Chile (1 degree), Beijing, Santo Domingo, Dar es Salaam (2 degrees), Cairo and Jakarta (3 degrees). If users accept this upward shift, adaptive buildings are possible. If not, hy- brid or air-conditioned solutions have to be developed. Comfort class 2 can never be reached in Delhi, meaning a fully adaptive building is not possible, a hybrid one like described would be the best option.
4 CASE STUDY RESULTS
4.1 International style standard office room
Figure 3 (left) shows the primary energy demand for the “international style” office room in all 15 locations. Where high solar transmission occurs through the façades, cooling demand is a dominant factor. The highest demand occurs in the hottest locations (Delhi, Cairo, and Jakarta).
Even in locations with moderate temperatures during summer such as Oslo and Hamburg, a cooling demand exists. In general, the level of primary energy demand is very high - a clear sign of the potential to optimise “international style” office buildings.
In order to cover the power demand for heat pump, artificial light and mechanical ventilation with PV modules (installed on the building’s envelope) a limited number of storeys is possible only; in the worst case (less than) one (Oslo, Reykjavik) up to 3 storeys (Mexico-City, Addis Ababa). Due to high demand of thermal energy for heating and especially for cooling a large es- tate is required to implement the geothermal system. To supply a five-storey building, the re- quired distances between buildings reach from 30 m (Mexico-City, Addis Ababa, Santiago de Chile) to more than 100 m (Delhi, Oslo).
Figure 3. Primary energy demand of standard office room for 15 locations, left “international style” and right “international style and optimized.
Generally, the attempt to develop a zero-energy urban situation using “international style”
buildings delivers unsatisfying results. The energy demand is too high. The necessity to reduce this demand further becomes aware in order to reach a satisfying situation.
4.2 Optimised standard office room
Before starting the optimisation of the room it has been necessary to decide whether the users are allowed to behave adaptive or not (e.g. dress code, company philosophy, number of users per operable window/thermostat etc.). If so, an adaptive building can be proposed and designed.
If it is necessary to switch during very hot periods to an air-conditioned building, a hybrid building can be designed. If even that is not possible, an air-conditioned building has to be de- signed. The cases examined in the following deal with air-conditioned buildings. This is not meant to reduce the relevance of adaptive building solutions but should demonstrate the poten- tial for energetically optimisations. Adaptive solutions will reduce the energy demand remarka- bly further! Figure 3 (right) shows the primary energy demand of an (air-conditioned) optimised room in comparison to the “international style” office room. The reduction potential is remark- able for all locations but differs for each one. For locations with cold winters, the optimised room has opaque façades with high thermal insulation, leading to a small reduction of heating demand. The reduction in power demand for artificial light has the biggest impact in locations with a clear sky, receiving 12 hours of daylight during the whole year (e.g. near the equator, see Cairo, Delhi, Addis Ababa). It is assumed, that no artificial light is used, if enough daylight is available.
Cooling demand can arise from high solar transmission through façades and/or a high out- door temperature. To counteract solar transmission, buildings can be optimised with adequately sized window areas and efficient shading systems. Important is however, that counteracting against very high (or even very low) temperatures with thermal insulation reduces their impact but not so perfect like a shading system for solar radiation. Thus, the highest heating demand occurs in locations with the lowest temperatures and the smallest opportunity of solar gains dur- ing winter (Reykjavik, Oslo). The highest cooling demand occurs in locations with the highest temperatures (Delhi, Jakarta) – here the potential for optimisation is limited. The highest reduc- tion in energy demand is found in locations where cooling demand for an “international style”
room arises from solar transmission (Santo Domingo, Singapore, Dar es Salaam, Sydney).
When trying to cover the power demand with PV modules, installed on the building’s enve- lope, it becomes clear once again, that only a limited number of storeys is possible. In the worst case again only (less than) one storey (Oslo, Reykjavik), 4 storeys and more (Cairo, Singapore,
