The Mexican government invests in various studies and programs in order to move the country towards sustainability.
- The goal is to promote the refurbishment of existing social housing units towards an optimal energy and environmental performance.
- Funding should be given as incentive for innovative measures and not for second and third-best measures.
by Susanne Theumer
A licensed architect working as senior scientist since 2008 at the Passive House Institute in Darmstadt, Germany. She is responsible for the Passive House building certifiers and involved in various pilot projects worldwide.
Mexico was the first country worldwide to implement a so-called NAMA study. NAMA stands for Nationally Appropriate Mitigation Actions and has the “goal to raise donor funding for upscaling Mexican efforts in energy efficient housing by showing energy efficient building concepts that are cost effective, proven to successfully reduce CO2 emissions and, at the same time, are adapted to the particular Mexican climate and conditions.” [PHI_2012]
With support from the German Environmental Ministry (BMUB) and within the framework of the Mexican-German Programme for NAMA-Programme, the Mexican government supported by GIZ and in collaboration with the German Passive House Institute (PHI), GOPA Consultants and IzN-Friedrichsdorf have developed the NAMA for Housing Retrofit. The technical design of this NAMA is based on the concept of the EnerPHit-Standard develop by the Passive House Institute promoting the refurbishment of existing social housing units step by step towards an optimal energy and environmental performance.
The NAMA-VE document (Nationally Appropriate Mitigation Actions, VE Vivienda Existente - existing housing) of Cost-optimised Standard for Social Housing retrofit in Mexico, elaborated in 2014, shows that the EnerPHit-Standard (see Figure 1: EnerPHit info box), is the most comfortable, sustainable and cost-efficient solution for all Mexican climates. Different retrofit options were calculated and compared with PHPP8 (2013) using a parameter method to represent a dynamic baseline scenario and combined with investment cost estimations for the current as well as future situation (when Passive House components will be available on the Mexican market). All of these options are defined to meet the EnerPHit-Standard in the long-run, even if the investor can now only pay for the first step such as a very energy-efficient fridge, opposed to a conventional fridge.
EnerPHit - the Passive House Certificate for retrofitsIt is not always possible to achieve the Passive House Standard (new constructions) for refurbishments of existing buildings, even with adequate funds. For this reason, the Passive House Institute has developed the “EnerPHit – Quality-Approved Energy Retrofit with Passive House Components” Certificate.
Significant energy savings of between 75 and 90 % can be achieved even in existing buildings, for which the following measures have proved to be particularly effective:
- improved thermal insulation (based on the principle: if it has to be done, do it right)
- reduction of thermal bridges
- considerably improved airtightness
- use of very good quality windows (there is no reason why Passive-House-suitable windows should not be used whenever the opportunity arises)
- ventilation with highly efficient heat recovery (again, Passive-House-suitable systems are very recommendable)
- efficient heat generation
- use of renewable energy sources
The examined retrofit steps were defined as follows:
First step: Replacement of old appliances by energy-efficient appliances, solar thermal collector for domestic hot water (DHW) generation.
Second step: Measures from step 1 as well as roof insulation (insulation thickness depends on the climate zone, see certification criteria), replacement of old windows by energy efficient windows (specification depends on the climate zone, see certification criteria), introduction of external shading elements, improvement of airtightness, special wall paint for a low absorptivity of the exterior walls.
Third step: EnerPHit-Standard (all components are energy efficient, as defined in the certification criteria, see [Build_cert_crit_2015]).
Realistic steps were chosen and could be separated further into smaller steps in order to serve as the basis for a future funding scheme. Important is that funding should be given as incentive for innovative measures and not for second and third-best measures.
Three different social housing building typologies (single-family home, row hose, apartment block) located in the four most representative Mexican climates [PHI_2015] were examined and the appropriate steps towards achieving the EnerPHit-Standard were agreed with Mexican governmental and financial institutions in order to find viable paths which have high chances of being pursued in reality. Even for the tropical climate, Passive House component qualities are clearly defined. For details, please see building certification criteria on www.passivehouse.com.
For the future implementation of the NAMA-VE, an energy consultancy scheme will be necessary, as well as a high degree of dissemination and promotion among the users. Early expert involvement is key to success: The investor will get support to design a customized overall refurbishment plan, including knowledge on the funding possibilities. However, the main advantage of the proposed strategy is that the end-user profits from day 1: all suggested efficiency improvements, see Figure 2, come along with an immediate comfort improvement. This ensures that not only lower energy costs but also feeling and experiencing better living conditions help persuade low- and medium-income families to invest in high energy efficiency. This way, a sustainable and cost-efficient solution can be achieved in the short- & in the longterm.
Retrofit steps for the row house typology. Source: Passive House Institute
As a result, and applying the boundary conditions as listed in Figure 3, the benefits of applying those components are numerous. The cost efficiency can be seen in Figure 4 where a calculation of a row house typology in Merida (hot & humid climate) is displayed, using both a current cost as well as a future cost scenario.
Boundary conditions for calculations. Source: Passive House Institute based on data of SENER.
Current (left) and future (right) costs scenarios for the row house typology in Merida (hot & humid climate). Source: Passive House Institute
Two built examples highlight the potential of high energy efficiency for Mexico and show that the theory can be put into praxis successfully.
Figure 5 shows the first certified Passive House in Mexico, an apartment unit in Mexico-City. It is climate adapted as it is one of the few Passive Houses without a ventilation system with heat recovery. In the moderate climate of Mexico-City, a simple extract-air system is sufficient.
First certified Passive House unit in Mexico-City, Mexico. Source: www.passivehouse-database.org, ID 2959
The second example is a retrofit of an apartment block. The energy balance of the building was set up with PHPP and proves that significant energy savings can be achieved via the application of Passive House components.
To sum up, in all cases the EnerPHit case proved to be the most economical option when looking at lifecycle costs. It can be concluded that the EnerPHit-Standard has once more proven to be the best option for achieving energy efficiency without compromising comfort or cost-efficiency. For the purpose of the NAMA-VE, which is the mitigation of CO2 emissions, the EnerPHit-Standard also proved to be the best investment possible. The NAMA-VE document [NAMA-VE 2014] demonstrates step-by-step approaches which all follow the EnerPHit path but allow for a realistic implementation, while improving living conditions by increasing comfort from the very first action.
Commissioned by the German Environmental Ministry (BMUB), the technical design of the NAMA-VE was developed for CONAVI (National housing commission) and SEMARNAT (Federal Ministry for Environment and Natural Resources) of Mexico on behalf of the GIZ (German International Cooperation Agency) in collaboration with GOPA Consultants and IzN-Friedrichsdorf.
[Build_cert_crit_2015] Passive House Institute: Building certification criteria, www.passivehouse.com, 2015.
[NAMA-VE 2014] Passive House Institute, IzN Friedrichsdorf, GOPA Consultants, NAMA Apoyada para la Vivienda Existente en México – Acciones de Mitigación y Paquetes Financieros. CONAVI, SEMARNAT, Mexico City 2014.
[PHI_2012] Passive House Institute, Technical Annex: Evalulation of social housing building types in Mexico. Study of energy efficiency, additional costs and CO2 mitigation as a basis for the preparation of the “Supported NAMA for Sustainable Housing in Mexico – Mitigation Actions and Financing Packages” presented at COP17 in Durban. Darmstadt, Germany 2012.
[PHI_2015] Theumer, Rivero, Passive House Institute, Cost-optimised Standard for Social Housing retrofit in Mexico: EnerPHit, Conference Proceedings of the 19th International Passive House Conference 2015, Leipzig, Germany.