Building Renovation Criteria

Several authors have identified the need to develop building renovation methodologies and criteria for common building stock (Casanovas, 2007; Eloy, 2012; Freitas, 2012; Teixeira, 2013a).

Either to ensure preservation of cultural and historic values or the commonality of intervention strategies.

Portuguese authors identified several factors that should lead to an increase in relevance of building renovation such as: (1) the abundance of the existing buildings, particularly housing,

68 in need of rehabilitation; (2) the stabilization of population growth; and (3) existing houses far exceeding the number of families. The tendency of increasing relevance of building renovation in detriment to new building construction is expected to continue, bringing Portugal closer to the European average (Carvalho, 2013; Eloy, 2012; Freitas, 2012; Teixeira, 2013a).

While the proposed methodologies and criteria were developed with specific case studies in Lisbon (Eloy, 2012) or Porto (Coimbra & Romão, 2013; Freitas, 2012; Teixeira, 2013a) they can be considered generic, e.g., Eloy’s methodology was applied in Kwiecinsky et al (2016) and Teixeira’s methodology is closely related with Casanovas RehabiMed (2007) and the Cartas.

Coimbra and Romão (2013) only propose a methodology, using Shape Grammars as a tool, and no explicit criteria are defined. Eloy’s methodology focuses on the concept design stage and the needed reorganization of the floorplan in the rehabilitation of houses. Her methodology defines evaluation criteria which are focused on the performance of the spatial organization. Thus, this methodology does not contribute to the definition of criteria for construction systems, as opposed to the work of Freitas or Teixeira.

Both Teixeira and Freitas propose intervention methodologies that start with a preliminary survey stage, and whose output is a diagnostic report that sets the stage for the projects. This preliminary stage must be scaled according to the type and scope of the intervention, but mainly serves to build knowledge of the existing structure when this is not available.

4.1.1 Teixeira Criteria

For Teixeira, interior partition walls are considered a medium intervention on the building which falls under the scope and type of a rehabilitation action. Teixeira’s criteria are not specific to this type of intervention and should be viewed with sufficient flexibility to allow for adaptation to particular cases (Teixeira, 2013a, p. 563).

Teixeira’s (2013a) criteria are based on a review of a large body of theoretical and prescriptive knowledge²¹. Although it was proposed as an intervention methodology for Porto historical center, its’ authors consider the methodology and criteria as a generic tool for intervention on built heritage, either monumental or common building stock (Teixeira, 2013b;

Teixeira & Póvoas, 2012). Nevertheless, their recommendations are specific to buildings built with traditional materials and construction techniques.

21 The prescriptive knowledge in this case refers to the recommendations of the Cartas and successive congresses since the 1904 International Congress of Architects, such as the Athens Charter for the Restoration of Historic Monuments of 1931, the 1964 Venice Charter, the 1975 European Charter of the Architectural Heritage, 1983 Appleton Charter, the 1987 Washington Charter, the 1995 Lisbon Charter, or the 2000 Krakow Charter.

69 Teixeira (2013a) defines a set of 12 intervention criteria:

JT1. Knowledge of the pre-existing building: a survey including but not limited to a geometrical, photographic, historical, structural aspects must precede the intervention.

JT2. Preservation of the pre-existing: It is preferable: “to repair than to demolish, but in case there is a demolition, it should be selective; to repair than to replace, but in case it is replaced, it is preferable to reuse.” (Teixeira, 2013, p. 565).

JT3. Adaptation to the context: Any intervention should respect the typological and morphological characteristics of the architectonic context. Thus, adjusting spatial requirements to the existing structure and maintaining original uses is preferable.

JT4. Integration with context: Harmonious integrations should be favored in detriment to confrontation or rupture with context.

JT5. Improving existing conditions: The interventions should contribute to improve or update the quality of buildings to current standards of comfort, hygiene, structural and fire safety.

JT6. Proportionality of normative demands: proportionality between the scope of the intervention and the normative and performative requirements

JT7. Reversibility of interventions and retrofits: Sufficient degree of reversibility of the interventions must be ensured and to this end the adopted solutions must be as close as possible to the existing ones in terms of material properties.

Irreversible solutions are those that cause damage to original structure if removed. Reparations should be done with original materials and techniques (this includes change of elements within a given system such as a beam in a wooden floor)

JT8. Preservation of pre-existing interventions: If a previous intervention holds historical value, it should be maintained.

JT9. Compatibility of materials and construction systems: Reusing existing systems and materials should be privileged. If repairing or replacement is necessary, the original methods should be privileged, otherwise compatible techniques and materials should be used.

JT10. Visibility of the intervention: New elements or parts should be visibly different from the original, in both materials and languages, nevertheless maintaining the harmony of the ensemble.

70 JT11. Population participation: participation of users should be encouraged in the project decisions that affect them, and if possible, they should participate in the renovation of their own houses conducting simple or small tasks.

JT12. Documentation of the intervention: all changes must be documented, stored, or published

For the specific case of changes to functional organization of interior spaces, which requires demolishing existing partitions walls and introducing new ones, Teixeira considers that the new elements should be distinguishable from the existing ones yet integrate harmoniously and use compatible materials. This recommendation is inherited from the Venice Charter (Teixeira, 2013a, p. 581).

Teixeira does not define performance criteria, static, acoustic, or thermal, for partition walls, yet admits those types of improvements are relevant for the exterior envelope of the building.

4.1.2 Freitas Criteria

Freitas principles for rehabilitation of old buildings (2012, p. 24) are in agreement with those proposed by Teixeira, and originate from similar sources, i.e., the cartas and ICOMOS recommendations. Yet, for the sake of completeness these are summarized below:

VF1. Minimize intervention: Only indispensable interventions should be conducted, and the scope of the intervention should be minimized while ensuring safety and durability.

VF2. Proportionality of safety and functionality demands: Changes of use should adapt functionality demands to the existing building. Normative safety demands should be replaced, when necessary, with other methods to ensure safety requirements.

VF3. Physical and chemical compatibility of materials: Materials introduced by the intervention should be compatible with the existing materials.

VF4. Reversibility of interventions: The interventions should be reversible, particularly on built heritage, allowing to reinstate the building to a previous condition. The aim is to not compromise future uses, and the possibility of the replacement of the current intervention in the future with more efficient and durable ones.

71 VF5. Respect for the pre-existing building, its history and original construction

techniques.

Freitas’ criteria can easily be mapped to Teixeira’s criteria: VF3 and VF4 are identical to JT9 and JT7 respectively, VF2 maps to both JT5 and JT6, VF1 is related with JT2, lastly VF5 can be related with the ideas expressed in JT3 and JT9. Hence, there is a clear agreement in terms of approaches to the intervention on existing buildings by researchers in this area. Reversibility of interventions clearly points to the need of thinking in terms of interfaces between systems and their capacity for disassembly. Which combined with the visibility criteria (JT10) offers a resolution to the apparent contradiction between open building and building renovation experts regarding the evolution of the space plan building layers. Lastly, criterium JT11 emphasizes the need of user involvement in the design process, and if the tasks are small, in the construction also.