Qatar Peninsula, according to the Koppen-Geiger climate classification, is located in a hot desert arid zone, where annual temperatures are greater than 18°C and the annual precipitation is lower than 250mm (Peel et al., 2007). Based on Qatar’s meteorology department (Q.M.D., 2016), the annual average temperature is around 27.3°C and the annual average relative humidity levels are around 61%, and the annual average rainfall level is around 6.6 mm ( see Figure 1).

Qatar along with the United Arab Emirates (UAE) are considered the two leading countries in the Gulf Cooperation Council (GCC) countries in adopting energy efficient policies (Willis, 2015). Although Qatar has not finalized a green building code yet, it has shown a number of efforts to enforce green practices, such as founding Qatar Green Building Council (QGBC) and initiating the Global Sustainability Assessment system, in addition to setting sustainability and energy targets for the country (Meltzer et al., 2014). As well as erecting a number of sustainable projects which include energy efficient measures such as the Passivhaus experimental project.

The Qatar Passivhaus project was initiated in 2013 by Qatar Green Building Council ( QGBC) and a real estate developer, BARWA real estate company. The high-performance levels of Passivhaus buildings were the trigger towards experimenting with the feasibility of the standard in the region. A team of experts was assigned to launch the project; QGBC, the AECOM group from London, KAHRAMAA, the Qatar General Electricity and Water Corporation, BARWA real estate and other partners such as ALMCO and Qatar Solar Technologies (Bryant et al., 2013). A site in Barwa development was dedicated to the project where the two identical buildings would be the specimen for the project.

The project was composed of two identical buildings, the Passivhaus villa (PHV), and the business as usual standard villa (STV), and was designed to house a family of 4 members. The villas comprised of the following; a living/dining space, 3 bedrooms, and associated service areas (see Figure 2).

Additionally, the buildings had a central courtyard and a patio which shaded the two main entrances of the villas. The two villas were located in a mixed-use development Barwa city, which was situated 15 km away from the capital, Doha.

The design of the villas respected the traditional architecture of the region through three main aspects; (a) a central courtyard, (b) a colonnaded patio and (c) the provision of motif movable panels around the courtyard that visually restricted the view towards the private section of the villas.

Although the two buildings were identical in their layout, the PHV was upgraded to reach to Passivhaus requirements and included the following sustainable features:

The performance of the villas was assessed through real-time measurements and thermal simulations. Two sets of virtual models were created for each villa, one representing the villa with occupancy and the other without. The villa’s outer fabric configuration assumed occupancy and assumed household appliances usage were simulated in the software Integrated Environmental Solutions –Virtual Environment (IES-VE). IES-VE is an innovative 3D sustainable analysis software pack used to measure and manage sustainable, efficient and affordable built environments (I.E.S., 2018).

Two weather sets were used, one representing the current climatic conditions and the other representing future climate. As wether files for Qatar were not readily available, Meteonorm a comprehensive meteorological reference weather generator tool was used to acquire the present day weather data (Meteonorm, 2016). For future projections, an excel worksheet based software package developed by the Sustainable Energy Research Group at Southampton University was used. The Climate Change World Weather Generator (CCWorldWeatherGen) is used to generate future weather files according to IPCC scenario A2, for the years 2020, 2050 and 2080 (S.E.R.G., 2015). In this paper, the comparisons will be presented for the present time and for 30 years from now, i.e. the 2050 weather data.

Furthermore, to study the performance of the building fabric, IES-VE was used to evaluate the robustness of the building fabric. This was assessed by de-activating the cooling option in IES-VE and evaluating the indoor temperature in both villas while conducting a comparison with the expected outdoor temperature.

Initially, both villas were to undergo an extensive monitoring period of around two years. During the first six months, the villas’ performance would be assessed without occupancy. Later on, occupant behavior will be further studied, first by monitoring their behavior without taking an induction on how to operate a Passivhaus building effectively, and the raming period would be assessed after providing the induction to the occupants. Unfoutunalilty, the monitoring process was not completed as originally planned. However, both villas went through a monitoring period of several weeks during the summer and winter of 2016/2017. Internal indoor temperatures and relative humidity levels were recorded in the habitable spaces ( living room and bedrooms) using data loggers that captured the indoor environment.

Additionally, three meter readings were used to assess the energy use in the villas, further interpolation was necessary to envisage the annual energy use in the villas.

According to the Passivhaus standards, stringent criteria need to be met to ensure both a reduction in energy use and a high degree of thermal comfort. Based on the simulation results, the Passivhaus in Qatar has met the stringent Passivhaus criteria in all criteria except for primary energy use, however, it is worth mentioning that the energy generated through the PV panels is sufficient to fully meet the load of the PHV.

In addition, Qatar PHV has failed in meeting the requirement for air-tightness. Based on the blower door test carried out at 50 Pas n50 in the PHV, the recorded infiltration rates were higher than the Passivhaus standard by around 40%. Other requirements such as the cooling demands, thermal comfort levels and the thermal transmittance of external surfaces were according to the standard ( see Table 1).

Table 2 continued

The PHV and STV thermal performance assessment were carried out though investigating three main performance indicators, (a) energy use, (b) indoor thermal comfort and (c) the thermal performance of the building envelope.

Additionally, with the consideration of the energy generated through the PV panes, the whole loads of the PHV could be met with a surplus load that could also be transferred to the local grid.

Figure 4 and Figure 4 illustrate the energy use in both villas in term of small power, lights and HVAC system usages. It is evident through the figures that most of the loads in both villas are exerted by the HVAC system. Furthermore, the measured HVAC energy use is less than the predicted energy use in the PHV, and vice versa in the STV, as the measured cooling demand is more than the estimated cooling demand through IES.

Differences between the measured and recorded data have been found, this may have been caused due to the manipulation of the setpoint temperature, or by the mispositioning of the data loggers or a possible error in simulation and calculations. Figure 6 illustrates the measured and predicted energy use in terms of HVAC use.

The present and future scenario indicate that the PHV will continue to use 50% less energy compared to the STV and that its full loads could still be met by the energy generated through the PV panels ( see Figure 7).

It should be noted that in the PHV a higher level of thermal comfort is expected especially throughout the projected year 2050. As presented in Figure 11, the occupants of the STV are expected to feel slightly warm during the hottest day of the year. This is expressed by the PMV figures of above (+1) during specific times of the day.

Although the PHV did not reach full Passivhaus standards, its design, construction, and commission involved rigorous specifications that were associated with various challenges. Starting from the design stage; with the lack of expertize in Passivhaus design, QGBC had to acquire a team of experts to deliver this project, which included AECOM, KAHRAMAA; the Qatar General Electricity and Water Corporation, BARWA real estate and other partners such as ALUMCO and Qatar Solar Technologies (Alumco, 2014). AECOM group of London were chosen to design the Passivhaus villa, owing to their expertize in Passivhaus design. A virtual dynamic model of both the PHV and the STV were created in IES-VE to study the thermal performance of the buildings under hot climates. Additionally, the Passive House Planning Package (PHPP) was also used to calculate the energy balance and annual energy demand in the villas, and to adhere to the Passivhaus standard certification process.

Upon completion of the drawings, and once commencing the construction, several challenges arose; first, due to the physical allocation of the design firm, continuous supervision by the architect was not feasible. However, QGBC team did not spare any effort to closely monitor the construction process. Second, construction workers were not customized to constructing airtight buildings, this resulted in a number of issues, which eventually affected meeting the airtightness benchmark of the Passivhaus standard. As mentioned in section 1.1, an airtight envelope with minimum thermal bridges is required to achieve Passivhaus standards. During the blower door test, several airgaps were found. the first was between the building envelope and piping and plumbing work, the second was found between the outer envelope and external fenestrations.

Finally, the third air gap was also detected along the ducting work. The PHV team tried to rectify these errors through the application of sealing materials, the airtightness of the envelope was reduced to the minimum, but still not the Passivhaus benchmark. The PHV yet stands as an example, of probably, the most airtight villa in Qatar.

Based on the literature review constructing to reach Passivhaus standard is one of the challenges that have been recorded especially outside of Germany (Müller & Berker, 2013). This is merely due to the fact that the standard was originally nourished in this region and that the workers have gained enough skill to construct buildings to meet the rigorous Passivhaus criteria.

Other challenges associated with the construction phase could also relate to the purchase of the energy efficient building systems, such as the cooling and the ventilation system. The purchase and implementation of a heat recovery ventilation system within buildings in the GCC is not common, this imposes two main issues, the first is related to the availability of such systems in the local markets and the second is associated with the level of knowledge to make a well-informed choice while selecting a high efficiency ventilation system.

Furthermore, with the construction of any energy efficient building, additional costs are inevitable. the inclusion of additional insulation, high-performance glazing, and energy efficient appliance in addition to the ventilation, heating/cooling systems all add up to raise the construction costs of such buildings. In on the studies that compared a Passivhaus to low energy building it was found that the option of a low energy building was much more feasible and practical in terms of the payback period (Audenaert et al., 2008). In case the case of Qatar the PHV construction cost were 15-20% more in comparison to the STV.

Furthermore, it was reported in a number of studies that one of the major challenges in Passivhaus buildings was related to effectively operating the ventilation system [(Brunsgaard et al., 2012); (Ridley et al., 2013)]. Although the PHV has not been occupied during the study period, it could be predicted that such a challenge would be expected. Especially during the cooler months where the cooling system may not be required and the ventilation system might need to be adjusted to ensure a continuous supply of fresh air in the villas.

Another challenge related to post-occupancy studies in Passivhaus buildings was denoted as the overheating problem (Brunsgaard et al., 2012). In the PHV and through the initial monitoring period this problem was not evident, with the use of the cooling system the indoor temperatures were maintained at the set point temperature of 23.5°C, it was also evident that during the winter times the indoor temperature dropped to around 18°C in the PHV and the STV. However, as occupancy patterns are unpredictable, the overheating problem may also rise in the future in the Qatar Passivhaus building or in other Passivhaus building in a hot climate, despite the use of the cooling system, and given the expected projection of future climate change.

The author would like to express sincere gratitude to the Qatar Green Building Council (QGBC), represented by Dr. Alexander Amato and Dr. Cynthia Skelhorn, who provided raw data and unlimited access to the Qatar Passivhaus project. The author would also like to acknowledge the support and help of Mr. Ahmed Al Abdulla, the CEO of BARWA Real Estate, and Mr. Simon Law of AECOM.