Bologna9-11 September 2015

31st InternationalPLEA Conference

Book of Abstracts

Conference ChairmanMario CucinellaArchitect, Founder of Building Green Futures, SOS School of Sustainabilityand Principal MCArchitects

Program ChairGiulia PentellaArchitect, Executive Director of Building Green Futures,Environmental Design Consultant and Researcher at MCArchitects

Organizing CommitteeMario Cucinella, Giulia Floriani, Giuliana Maggio, Giulia Pentella,Michela Grosso, Alba Fagnani, Patrizia Pizzi

Editorial TeamMario Cucinella, Giulia Pentella, Alba Fagnani, Luca D’Ambrosio

Hosting OrganizationBuilding Green Futures, non - profit organizationVia Barozzi 3/a, 40126 Bologna, Italyhttp://www.buildingreenfutures.org/

TitlePLEA2015 Architecture in (R)Evolution – Book of Abstracts31st International PLEA Conference – Bologna 9-11 September

CopyrightBuilding Green Futures, BolognaFirst published 2015ISBN: 978-88-941163-0-4ISBN: (eBook, Proceedings) 978-88-941163-1-1

Graphic Design ProjectLuca D’Ambrosio

PublisherAss. Building Green Futures, Bologna

All rights reserved.No part of this publication may be reproduced, distributed, transcribed, translated in any language or computer language, stored in a retrieval system or transmitted in any form or by any means, including photocopying, recording or other electronic or mechanical methods, without the prior written permission of the publisher and the author(s). This publication was prepared from the input files supplied by the authors. The publisher is not responsible for any use that might be made of the information contained in this publication.

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This paper focuses on the development of a modular construction system of rural low-cost housing and low environmental impact, using mud and bamboo. The system applied traditionally is known as “wattle and daub”. This system involves the use of a vegetal warp coated with a mixture of soil stabilized with lime and rice straw. This traditional construction technique has been used since ancient times in architecture without architects, mainly in American continent rural areas with slight variations from one region to another. It is intended that the final cost of the basic module is around $80 USD a square meter including facilities and finishes. Rigidity is achieved through a geodesic dome structure V1 frequency. The combination of the dome and the wattle & daub confers advantages such as seismic resistance, durability, ease of construction, optimization of natural resources and the use of local materials. The preliminary design was a basic module of 15 square meters in order to permit the gradual growth of the house. Original purpose was to make hygrothermal performance inside the prototype. However, prototype is not completed in scheduled time due to delay of approval on environmental impact for the use of native bamboo (Otatea acuminata ssp. Aztecorum) by the federal environmental authority. Instead, it was determined the monitoring with specimens of 0.25 x 0.25 m. x 0.11 m. This allowed the analysis of three different binder samples combinations: lime/sand, earth/straw and cement/sand. Recording equipment used was HOBO onsetcomp U12-012 for temperature and RH. Also thermal conductivities of the materials were determined using a conductivimeter KD2PRO. Measurement data mentioned above are intended to describe the thermal performance of materials in different configurations wattle & daub and set up an approximation of a mathematical model of the global heat transfer coefficient of wattle & daub in a stationary state.

low-cost housing, wattle & daub construction system, bamboo wattle & daubKEYWORDS:

WHICH ARE YOUR ARCHITECTURAL (R)SOLUTIONS TO THE SOCIAL, ENVIRONMENTAL AND ECONOMIC CHALLENGES OF TODAY?Research Summary

MODULAR RURAL HOUSING OF LOW COST, LOW ENVIRONMENTAL IMPACT AND SELF-BUILDABLE MADE OF BAMBOO WATTLE & DAUB & DAUB IN COLIMA, MEXICOMiguel Elizondo-Mata, Carlos J. Esparza-López,Jorge A. Ojeda-Sánchez, Adolfo Gómez-Amador,Marcos González-Trevizo, Juan R. González de Loza

Universidad de Colima

Schematic model of prototype

Modular rural housing of low cost, low environmental impact and self-buildable made of BAMBOO WATTLE & DAUB & DAUB in Colima, Mexico.

Miguel Elizondo-Mata Universidad de Colima elizondomata@ucol.mx Carlos J. Esparza-López Universidad de Colima cesparza@ucol.mx Jorge A. Ojeda-Sánchez Universidad de Colima jojeda1@ucol.mx Adolfo Gómez-Amador Universidad de Colima amad@ucol.mx Marcos González-Trevizo Universidad de Colima gonzalez_marcos@ucol.mx Juan R. González de Loza Universidad de Colima juanramon@ucol.mx

Fig 1: Schematic model of prototype

Research summary This paper focuses on the development of a modular construction system of rural low-cost housing and low environmental impact, using mud and bamboo. The system applied traditionally is known as “wattle and daub”. This system involves the use of a vegetal warp coated with a mixture of soil stabilized with lime and rice straw. This traditional construction technique has been used since ancient times in architecture without architects, mainly in American continent rural areas with slight variations from one region to another. It is intended that the final cost of the basic module is around $80 USD a square meter including facilities and finishes. Rigidity is achieved through a geodesic dome structure V1 frequency. The combination of the dome and the wattle & daub confers advantages such as seismic resistance, durability, ease of construction, optimization of natural resources and the use of local materials. The preliminary design was a basic module of 15 square meters in order to permit the gradual growth of the house. Original purpose was to make hygrothermal performance inside the prototype. However, prototype is not completed in scheduled time due to delay of approval on environmental impact for the use of native bamboo (Otatea acuminata ssp. Aztecorum) by the federal environmental authority. Instead, it was determined the monitoring with specimens of 0.25 x 0.25 m. x 0.11 m. This allowed the analysis of three different binder samples combinations: lime/sand, earth/straw and cement/sand. Recording equipment used was HOBO onsetcomp U12-012 for temperature and RH. Also thermal conductivities of the materials were determined using a conductivimeter KD2PRO. Measurement data mentioned above are intended to describe the thermal performance of materials in different configurations wattle & daub and set up an approximation of a mathematical model of the global heat transfer coefficient of wattle & daub in a stationary state. Keywords: Low-cost housing, wattle & daub construction system, bamboo wattle & daub

1. Introduction In Mexico, the deficit of decent housing for the people has not been covered. This despite the progress in this area by government institutions. In the state of Colima, although this problem is not as critical as in other states, housing is a problem to address, particularly in the municipalities of Ixtlahuacán and Comala. The aim of this paper is the design and construction of a prototype low-cost module with the combination of technologies. This prototype will help raise the level of efficiency of new housing and promote the improvement of rural living, with an emphasis on optimizing the use of water and energy resources. The research project which aims to start with the realization of an architectural project, considering the domes and wattle & daub. Architectural envelope is also considered. Such enclosure consists, constructively talking, in a wall-ceiling system. The project continues with the completion of the analysis of their qualities of climate adaptation, seeking the comfort of end users. As a viable alternative to solve this problem in rural areas, it is proposed to use traditional knowledge combined with Fuller's geodesic domes. Utilization in the light of technological and scientific advances of our time is possible combinations of geodesic domes, with traditional wattle & daub technique, and the use of bamboo Guadua or weighted. This allows a quick and simple construction, with a smooth technology transfer. The construction system wattle & daub is used from immemorial times not only in Colima and western Mexico, but in most of the Americas. It originally consisted of interlacing bamboos or some type of rod, which is then coated with a binder mixture of soil clay and straw. The technique may vary by region but the system is the same. In the region there are several

endemic species of bamboo, including the Otatea acuminata ssp. Aztecorum used in the construction of houses. Additionally currently existing commercial plantations of Guadua angustifolia Kunth, originating in South America, in various places in the state of Colima in an approximate area 70 hectares. Also over the next two years will begin the first commercial exploitation of this renewable material, suitable for building (Colima PRODUCE Foundation, 2014). A very interesting situation arises regarding the availabilities of bamboo, because although there are some native varieties as already mentioned above, today has begun commercial plantations in the short term may provide Guadua angustifolia Kunth, Colombian variety introduced in Mexico, with exceptional qualities for construction. Moreover, the Faculty of Architecture and Design at the University of Colima, during the past seven years has promoted training regarding the construction and restoration of buildings of raw land. It has generated an interesting critical mass of professors, but also students of architecture, which enables these topics, theoretical and practical way. Additionally it is a priority for the teaching of architecture in the new generations the knowledge and use of alternative materials and systems, environmentally friendly and energy-wise, as rural housing self-built assisted through with geodesic domes bamboo and daub with raw land stabilized with lime and straw, with thermal comfort conditions, costing 40% less than the construction made with conventional materials and with minimal environmental impact. Regarding the geodesic domes they are considered as structures that have advantages over conventional construction: delimitation of usable area, seismic resistance, durability and constructive way, among others. In this case,

the use of simpler geodesic dome was proposed, the frequency V1 dome (According Fuller), consisting of a truncated icosahedrons (Fig. 2).

Fig 2: Truncated icosahedrons as a simple geodesic dome frequency V1. 2. Method Colima is located in the southwest of Mexico near the Pacific coast. Its location is 19°12’50” north latitude and 103°43’21” west longitude and is approximately 433 meters above sea level. Temperatures range between 15.0°C and 34.0°C throughout the year and relative humidity ranges from 30.04% and 87.91%. It is considered as hot sub-humid. Field tests were made for the characterization of the soil of the surroundings, commonly used for the construction of the wall-ceiling system; these field tests are the precipitation and absorption of the material. Once characterized the earth, it was identified that consists of 35% clay, 60% sand and 5% silt, indicating that the land is suitable for building. The optimal mixture and the amounts of lime and straw required to stabilize were determined. The

proportion of land / straw / lime was determined in 10:4:1. 2.1 Samples In order to be able to analyze the thermal behavior of the building system, three specimens with different wall components were made with a section of 0.11 m and a dimension of 0.25 x 0.25 m as described below: PB-1. Wattle & daub wall specimen

composed of Guadua angustifolia Kunth downtown, soil mixture / rice straw / lime paste in proportion 10/4/1, with a thickness of 0.025 m each side wall, finished of lime/sand proportion 1:3 with a thickness of 0.02 m on either side of the wall (Fig. 3)

Fig 3: PB-1 specimen with earthen/straw mix and Guadua angustifolia kunth. PB-2. Wattle & daub wall specimen

composed of Guadua angustifolia Kunth at the center, and cement-sand mortar in a 1:3 to both sides of the wall (Fig. 4)

PB-3. Wattle & daub wall specimen composed of Otatea acuminata ssp. Aztecorum center, soil mix / rice straw / lime paste in proportions 10/4/1, with a thickness of 0.25 m each side wall, finished lime/sand proportion 1:3 with a thickness of 0.02 m on either side of the wall (Fig. 5)

Fig 4: PB-2 specimen, with Guadua angustifolia kunth, and sand/Portland cement mortar.

Fig 5: PB-3 specimen, with earthen/straw mix and Otatea acuminate ssp. Aztecorum. Small modules were made with the specimens and Styrofoam plates (Fig. 6), with dimensions of 0.11x 0.25x 0.25 m in order to monitor the thermal behaviour at the interior of the module. The modules were oriented south, direction with high solar exposition. The monitored variables within the module were: dry bulb temperature (TBD) Relative Humidity (RH) and Black Globe Temperature (GT). Dry bulb temperature and relative humidity were registered with data logger HOBO U12-012 which has an accuracy for dry bulb temperature of ± 0.35 [°C] and relative humidity accuracy of ± 2.5 [%]. The globe temperature was taken with the data logger Hobo H08-004-02 with a temperature accuracy

of ± 0.35 [°C]. The monitoring time was 6 days, from April 30th to May 5th, 2015, at intervals of one hour measurement. The data of the surroundings, are considered, in a first approximation with the mean ambient temperature. The main objective of measuring the variables of dry bulb temperature, globe temperature and relative humidity was to characterize the thermal behaviour of wattle & daub with different compositions of material. The results are widely discussed in the results section.

Fig 6: Module built of each sample and Styrofoam plates oriented south. Additionally samples of each material separately were performed 0.085 x 0.085 x 0.055 m to measure the thermal conductivity of each. P-01. Guadua angustifolia kunth specimen. P-02. Soil/straw/lime proportion 10:4:1

mortar specimen. P-03. Lime/sand proportion 1:3 mortar

specimen. P-04 Cement/sand proportions 1:3 mortar

specimens.

The physical property of interest to measure was the thermal conductivity. The measurements were performed with the measuring equipment KD2 PRO of Decagon Devices. It has a RK-1 sensor with an accuracy of ± 0.02 W / mK for the thermal conductivities range from 0.1 to 0.2 W / mk. Thermal-ceramic polysynthetic compound paste was used brand Arctic Alumina to facilitate thermal contact between the sensor and the test pieces. Measurements of thermal conductivity require a minimum sample size of 0.015 x 0.015 x sensor length. A hole of 11/64 “(0.0043 m) was made in the sample to introduce the sensor covered of thermal contact paste. Sheets of bamboo were made for the vegetal specimen, so they had contact each other, once connected the necessary drilling was conducted for measurement. The measurement results are shown in the results section. 2.2 Global Heat Transfer Coefficient (GHTC) wattle & daub model In a first approximation for describing the thermal behaviour of wattle & daub, the convection heat from the surrounding environment and heat transfer through wattle & daub were considered. Different composite materials can be approximated as a series of thermal resistances. To model the above considerations it is assumed: 1) heat transfer occurs in a stationary state and unidirectional. 2) there is no heat generation inside the wattle & daub. 3) the layer thicknesses x, of the different materials are uniform.

4) the Guadua angustifolia Kunth and Otatea acuminata ssp. Aztecorum cover the entire cross-sectional area. 5) the thickness of each layer of material comprising the specimen are known, as well as their cross-sectional areas (A). Whereas the experimental samples are subjected to environmental conditions, it is considered that heat is transferred by convection from outside to inside through the different layers of material. The convection heat is defined as:

, (Eq. 1)

where h is the convective coefficient.

Heat transfer by conduction between the different layers in the wattle & daub is defined by the following expression: , (Eq. 2) where k is the thermal conductivity of the material. Whereas both previous forms are heat transfer, it is possible to generate a thermal resistance model that will define the overall coefficient of heat transfer, the total thermal resistance of wattle & daub is defined by the following expression:

. (Eq. 3)

The global heat transfer coefficient is the inverse of the total thermal resistance of wattle & daub and can be defined by the following equation:

. (Eq. 4)

In Eq. (4), it is considered that the outside heat transfer coefficient, hout, and inside, hint, are equal. Furthermore, the terms x1, k1, x2 and k2 refer to the thicknesses and thermal conductivities of the preceding and following layer of vegetable materials, as the case may be; x3 and k3 terms refer to the thickness and conductivity of bamboo or otate. The global heat transfer coefficient can be calculated for different configurations of the material, this allows a calculation of the transfer in the direction normal to the wall or cover wattle & daub, using data such as area, the outside temperature and interior space, the expression for calculating the heat flow is as follows;

. (Eq. 5) An approximate model to consider the gains likely to have a wattle & daub wall or cover due to solar radiation exposure over a day or a period of time, can be calculated by the following equation:

, (Eq. 6) where Ir is irradiation [w/m2] and α is absorptivity [dimensionless]. The above amounts vary throughout the day so you can set the amount of heat qrad for a certain time and assess their thermal performance of wattle & daub with heat gain due to solar radiation. The total heat flow can be calculated from Eqs. (5) and (6), thus, wattle & daub total heat perceived is calculated by the following expression:

. (Eq. 7)

The model of heat transfer in unsteady state can be defined from a differential equation solving the predominant direction of the heat transfer, the time variable and setting the appropriate boundary conditions. The methodology widely developed is available at Özisik, (1993). 3. Results and design potential The results of measurements of temperature and relative humidity, made on the specimens with different configurations of materials, show the thermal behaviour of traditional wattle & daub, consisting of a mixture of soil / rice straw/ lime paste with Guadua angustifolia Kunth at the center, called PB-1 sample. The behaviour of the dry bulb temperature (TBD) of the specimens can be seen in Fig. 7.

Fig 7. Inside Dry-Bulb temperatures comparison. The behaviour of the specimen composed of Otatea acuminata ssp. Aztecorum, (PB-3) has an offset in temperature with respect to the specimen bamboo (PB-1) and bamboo cement specimen (PB-2). The dry bulb temperature of the specimen of traditional wattle & daub, PB-1 sample has a lower temperature than the

temperature inside presenting the specimen PB-2, composed of cement-sand mortar. In Figure 8, it can be seen that the amount of humidity in the sample PB-2, shows a decrease in the hours of highest solar incidence; however the traditional wattle & daub specimen PB-1, maintains a relative humidity percentage virtually unchanged, about 91%. The PB-3 specimen, which is the wattle & daub with Otatea acuminata ssp Aztecorum has a high relative humidity in the interior, up 95%. The causes of this behaviour may be due to the amount of initial moisture content at the time of its construction. The otate used, keeps a smaller volume ratio with respect to the other materials that make up the wattle & daub.

Fig 8. Inside RH comparison. The black globe temperature is reported from April 30th to May 1st 2015 due to measurement problems with data loggers, measurement was not continued during the measurement period. Possible causes may be due to the initial handling by placing instruments inside the specimen. Data black globe temperature are shown for May 1st 2015, the curves of wattle & daub specimens can be seen in Figure 9. Black globe temperature for the specimen made of wattle & daub with Guadua

angustifolia kunth, fits as befits the radiation perceived throughout the day. When it has a low surrounding temperature, black globe temperature decreases, and increases by the time of the day with higher temperature. The PB-3 specimen composed of wattle & daub with acuminata ssp. Aztecorum, presents a delayed temperature behaviour. The behaviour of this sample is as if it would store radiant energy. The specimen PB-2 composed of cement mortar and Guadua angustifolia Kunth has values close to 40 ° C near by the moments of more solar incidence, the radiant temperature is variable over time.

Fig 9. Black globe temperature comparison. In Figure 10, the results of measuring conductivity of the materials composing wattle & daub are presented. 10 observations were obtained with 10 minutes duration each. They presented a correlation error between the measurement and the algorithm in the order of 0.01. Average conductivity values of materials are presented. The thermal conductivity measure of the Guadua is 0.15 W/mk, and this value is close to the reported by Hidalgo (2003), where thermal conductivity is 0.11 W/mk. With the data in Figure 10 we can calculate the global heat transfer coefficient.

Specimen Type Thermal conductivity [W/mk] Thickness [m]

P-01 Guadua Angustifolia 0.1575833 0.013 P-02 Mortar/soil/straw/lime 0.3313076 0.025 P-03 Mortar/lime/sand 0.1650000 0.02 P-04 Mortar/cement/sand 0.5154166 0.02

Fig 10. Thermal conductivity specimens results.

Sample U [W/m2K] PB-1 1.086623 PB-2 1.180676

Fig 11. Global Heat Transfer Coefficient of specimen PB-1 and PB-2. Calculations were performed with the PB-1 and PB-2 specimens; in order to compare the potential for heat transfer with wattle & daub of different composition (Fig. 11). For the PB-3 specimen, no thermal data is registered because the Otatea acuminata ssp. Aztecorum geometry, the diameter is of the order of 1 cm, so it is necessary to generate an adequate test piece, to facilitate the measurement of thermal properties 8. Conclusions The results show the possibility of traditional construction with wattle & daub compound of materials from the region of the state of Colima, Mexico. Thermal performance suggests that the traditional wattle & daub of the specimen PB-1 has greater thermal insulation, compared with wattle & daub composed of cement and bamboo as it is the specimen PB-02. As for the calculation of the global heat transfer coefficient, it can be concluded that a wall of a given area, present less flow of heat transfer in a wall made of wattle & daub compared to a traditional cement-bamboo. Independently of the results the constructive system of wattle & daub in the tree analyzed cases, shows viability in order to be adopted in

sub-humid warm climates, and the spatial scheme proposed based on the geodesic dome frequency V1, results as an alternative faced to the conventional auto-construction, as two of these models are equivalent in area to the minimum housing supported by the Mexican government agencies but its economic cost is equivalent to 35%. Acknowledgements Arch. Omar González from Consejo Estatal de Bambú of Colima, who provide Guadua specimen, and to the students of 2nd and 8th semester of Architecture of Universidad de Colima. 9. References Aristizábal, V.(1999).Guía para autoconstrucción

utilizando la guadua como elemento principal.Colombia: Coop. Colombo-alemana

Bárbaro,G.(2007). Transformación e industrialización del bambú. Barcelona

Castro, D.(1985) La guadua, un material versátil. Bogotá: FES

Giraldo, E.(2007). Una alternativa sostenible: la guadua. Colombia: CRQ

Guerrero, L.(2012). Arquitectura en tierra II.Bogotá. Apuntes U. Xaveriana

Hidalgo, O.(2003).Bamboo the gift of the gods.Colombia: D´VINNI LTDA

Minke,G.(2012). Building with Bamboo. Switzerland. Birkhauser Basel

Özisik,N.(1993) Heat Conduction, N.Y: Wyley Sánchez,A. (2011) Bambú. Barcelona: Watkins, K.(2015). In 4 Days, 100 Volunteers Used Mud and Reeds To Build This Community Center in Mexico, May 9, 2015, site www.archdaily.com/628163

Bologna9-11 September 2015

31st InternationalPLEA Conference

Book of Abstracts

Conference ChairmanMario CucinellaArchitect, Founder of Building Green Futures, SOS School of Sustainabilityand Principal MCArchitects

Program ChairGiulia PentellaArchitect, Executive Director of Building Green Futures,Environmental Design Consultant and Researcher at MCArchitects

Organizing CommitteeMario Cucinella, Giulia Floriani, Giuliana Maggio, Giulia Pentella,Michela Grosso, Alba Fagnani, Patrizia Pizzi

Editorial TeamMario Cucinella, Giulia Pentella, Alba Fagnani, Luca D’Ambrosio

Hosting OrganizationBuilding Green Futures, non - profit organizationVia Barozzi 3/a, 40126 Bologna, Italyhttp://www.buildingreenfutures.org/

TitlePLEA2015 Architecture in (R)Evolution – Book of Abstracts31st International PLEA Conference – Bologna 9-11 September

CopyrightBuilding Green Futures, BolognaFirst published 2015ISBN: 978-88-941163-0-4ISBN: (eBook, Proceedings) 978-88-941163-1-1

Graphic Design ProjectLuca D’Ambrosio

PublisherAss. Building Green Futures, Bologna

All rights reserved.No part of this publication may be reproduced, distributed, transcribed, translated in any language or computer language, stored in a retrieval system or transmitted in any form or by any means, including photocopying, recording or other electronic or mechanical methods, without the prior written permission of the publisher and the author(s). This publication was prepared from the input files supplied by the authors. The publisher is not responsible for any use that might be made of the information contained in this publication.