energy efficiency pathology case in portugal with suggested solutions

UNIVERSIDADE DO MINHO

DEPARTAMENTO DE ENGENHARIA CIVIL Patologia e Reabilitação Não-Estrutural das Construções.

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ENERGY EFFICIENCY PATHOLOGY CASE

AHMAD ALSHAGHEL

Introduction

The case has been chosen in Portugal, where almost 75% of the total EU floor space are considered residential buildings (Economidou, M., et. al. (2011)). Therefore energy efficient refurbishment is a key issue in those buildings. Implementing EPBD-recast principles, making it more energy efficient and comfortable. Also, the majority of the residential houses built in Portugal before 2006 currently considered in the need of energy rehabilitation, (Sousa, J. R., Silva, S. M., & Almeida, M. G. D. (2012)) For residential buildings, the energy efficiency, mainly thermal, retrofitting is considered a complex decision making process that needs the approval and the cooperation between all stake holders starting from owners, residents, professionals and managers.

Retrofitting process

While the costs of energy rise and inhabitants demand more comfortable interior environments, the need to undertake energy retrofits increases. However, expensive retrofit projects tend to be avoided because the final improvements may not be sufficient. Therefore, a simple detailed plan must be considered with the most important stages; 1- analyzing the energy consumptions rate with the weather and environment status. 2- Evaluation the energy savings and the cost final savings. 3- The overall performance of the retrofitting project should be declared and followed.

Building review

A multi-story residential apartment block situated in Azurém, Guimarães, at the north of Portugal, built up in the 1970`s. The building is a three stories concrete building with units with L-plan scheme and placed in between relatively taller neighbor buildings, as seen in Figure 1. The building consist of seven sub-apartments units within each floor in them two flats. The main façades are NW/SE oriented, as in Figure 2.



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Figure 1, study case in Portugal, building location

Figure 2, the facades direction with the general location

Climate and Environment Climate in the city of Guimarães is generally warm but rainy, with relative high humidity. The average temperature varies from around 12 to maximum over 25 and it could be seen clearly in Figure 3. Also, the city has a high rainfall all the year, with percentage of more than 1200 mm. Figure 4 shows it better (worldweatheronline.com 2015).

Figure 3, Average Temperature table



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The high humidity has a massive effect on the moisture problems and pathologies which results in more energy challenges. The city of Guimarães has a fairly high humidity rates with approximately 80% most of the year. Figure 5

Figure 5, Average humidity in the months of the year Existing HVAC and DHW systems

For the heating purpose, there is no heat distribution system in the building’s flats. The

used heating devices are electric heaters units. Also, there is no air conditioner in any

flat, ventilation is provided naturally. Also for the domestic hot water usage, a gas

heater in every kitchen provides hot water for each flat. The cooking devices are either

natural gas or electricity operated. Figure6

Figure 4, Average rainfall table



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Figure 6, shows the used systems for DWS, Heating, Ventilation and cooking

Pathologies types

The absent of renewable energy systems:

Renewable energy is considered one of the most important factors in the sustainably

buildings. And the absent of all renewable sources results in and more opposition to the

near zero energy building principle. Also, buildings with no renewable energy

performance is considered on the lowest sustainable building according to the 7th

parameter in SBTools 2012 guide.

The insufficient insulation systems.

The insulation, thermal, plays a significant role in securing more efficiency in energy

terms. Therefore, the lacking for such insulation will produce problems not only in

heating and cooling needs but also in moisture which will lead to fungus, dampness and

health problems.



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The Figure 7 clarify the problems in the house as the walls and facades insulation is

deficient, which resulted in moisture problems and more pressure on the heating and

cooling systems to overcome its results. Moreover, it will add more costs and decrease

sustainability on both social (health) and economical (costs) areas.

Figure 7, the insulation in the wall and the results of moisture.

Material Pathology

Many of used materials need to be maintained in a regular schedule and also to be

changed according to the needs. The lack of maintenance produces more problems

starting from the moisture problems, the reducing of energy efficiency. Such problems

can obviously be seen in the clear single-glazed aluminum windows used in glazing with

low quality materials, the same goes for the frames of doors and windows. Figure 8



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Figure 8, low quality glazing and framing materials

The over ventilation problem

The building sustained a natural ventilation system through the presence of the wide

windows and openings. However, the incorrect design with the low quality covering

materials resulted in more ventilation, yet less energy efficiency. The very wide

openings (more that 60% of the wall area) formed a satisfactory ventilation flow but

with needs to more heating in winter and more cooling in summer. Figure 9.



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Figure 9, wide openings problem

Proposals and suggested solutions

the purpose of energy demand reduction under the influence of building envelope retrofits, scenarios were run as wall refurbishment, wall and window refurbishment, wall, window and roof refurbishment; wall, window, roof and ground floor refurbishment respectively. Increasing the efficiency of resource use while reducing building impacts on human health and the environment. Covering numerous eco-friendly systems will be the guidelines for the process.

The building materials were assumed to be changed with the ones which have

better thermal conductivity

Green roofs are a passive cooling technique that stop incoming solar radiation from reaching the building. Many studies have been conducted about their benefits in winter heating reduction as well as summer cooling (Castleton, H. F., et al 2010)



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Renewable Energy Technology Integration A real simulation for the building needs and the solar thermal simulation should be conducted to reach the best installment for the building. Solar Thermal system (PV panels) will be an efficient system to increase the renewable energy and reduce the consumption of non-renewable resources, which will lead to more efficient overall performance.

Building review according to the proposals

The approach to achieve a more energy efficient building is to reduce the energy demand and then to supply part of the reduced demand with a renewable energy system. Demand reduction could be accomplished through the following building envelope improvements:

• Replacement of the glass of windows and doors and the original single-glazed window units with new insulated glazing units with a low-e coating.

• Replacement of the original roof, which is with no insulation.

In order to supply heat for the domestic hot water (DHW) system, a solar collector could be installed on the roof.

Changing the roofing system with Green roofs as the reduction of heat flux and solar reflectivity in summer the exposed area of a black roof

Replacement of the old common area lighting, also maintain all the electrical devices.

Replacement of the windows and doors frames with enhanced ones will lead to improve window air tightness and increase energy efficiency.

Those changes will make it easier to maintain the thermal control in the units. Through reduced air leakage and improved thermal resistance. Eventually the improvements will enhance the energy efficiency in the building and reach more sustainable building.

Cost evaluation



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The cost estimation for retrofitting projects is an essential stage, therefore it should

be studied based on ground studies and simulation with real time measurements. Also,

the thermos physical properties of existing building envelope components in terms of

U-values should be estimated, with the budget of the stake holders with the preferred

most possible level of retrofitting.

Conclusion

The energy efficiency retrofitting of the Portuguese residential buildings is a major process in the country development. Many of the buildings face those problems, therefore, it is necessary to analyze each situation individually to investigate and decide the best solutions for each case. The rehabilitation of energy efficiency will not only reduce energy needs but also will improve pathologies related to dampness and humidity effects. Each case should be studied in the light of retrofitting guides to improve the situation and have a clue about the perspective costs and benefits. References

[1] Economidou, M., et. al. (2011). Buildings Performance Institute Europe (BPIE) Europe’s buildings under the microscope: A country-by-country review of the energy performance of buildings. Brussels. Buildings Performance Institute Europe. [2] Worldweatheronline.com, "Guimaraes, Portugal Weather Averages | Monthly

Average High And Low Temperature | Average Precipitation And Rainfall Days | World

Weather Online". N.p., 2016. Web. 24 Feb. 2016.

[3] Sousa, J.R., Silva, S.M. and Almeida, M.G.D., 2012. Energy rehabilitation of

Portuguese residential building stock through its transformation into NZEB.

[4] Castleton, H.F., Stovin, V., Beck, S.B.M. and Davison, J.B., 2010. Green roofs;

building energy savings and the potential for retrofit. Energy and buildings, 42(10),

pp.1582-1591.

[5] SBTool 2012 assessment framework. Nils Larsson, iiSBE, December 07, 2012

energy efficiency pathology case in portugal with suggested solutions

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