E++ & ILA Studios: Karakorum National Park
Central Karakorum National Park, Pakistan
The Central Karakoram National Park (CKNP) is one of the most important parks in Pakistan, bordering China, Afghanistan and India. In order to promote sustainable development of the territory, the Italian Committee Ev-K2-CNR, through the SEED project, is working in the region to support the deployment and management of the park and improve the quality of life and livelihoods of local people. Among the key focuses of the project is the design of a new sustainable headquarters building for the park.
E + +
E + +, an expert company in energy technology, focused on renewable sources and energy efficiency and ILA studio architects, have worked together to successfully evaluate and improve the energy efficiency of an integrated environmental design for the proposed head office building of the Central Karakorum National Park in Pakistan. Using the IES Virtual Environment the analysis allowed them to assess the actual sustainability of the model and the possible improvements that could be made to make it a much more energy efficient and high performing design.
To ensure the energy efficiency of the building, E++ and ILA Studio worked in collaboration to analyse the predicted energy usage of the building right from the early stages of the design process. Taking into account climatic and environmental considerations, they carried out the analysis using VE-Pro modules MacroFlo, ApacheSim, ApacheHVAC and ApacheCalc.
The building is to be a 500 square meter double storey office building. The construction techniques and materials were chosen from the local vernacular construction habits. These included a massive stone and concrete skin, wooden floors and wooden single glazed windows with traditional external operable wooden blinds. From the building services point of view a standard boiler and radiator system was chosen for during the winter season, while no air conditioning is provided for summer.
The initial simulation showed the building to be of poor performance with regards to heating, primary energy consumption and summer comfort. The winter thermal balance was mainly affected by the conduction losses through the low performance glazed façade, convective losses due to the high ventilation rate, and a very low external temperature in winter. Thus resulting in more than 88 kWh/m2y yearly primary energyheating consumption.
The summer indoor comfort was compromised by the high solar and internal heat gains. Therefore more simulations were carried out to evaluate the right blind operation and ventilation strategy. The ventilation strategy was evaluated in relation to the effect it has on summer indoor comfort of Daily Cross Ventilation (CV), Night Ventilation (NV), and a combination of both CV + NV. This showed a consistent improvement of indoor comfort levels and a reduction of indoor air temperatures, with less than 200 hours hitting temperatures in summer above 26°C (as a sum of all the hrs in the 7 occupied rooms).
Given the poor performance of the glazed façade resulting in high heating consumption and low indoor comfort levels, an analysis of the impact of a series of improvements was undertaken. An improved design proposal was created taking in to consideration low budget and limited design changes, using traditional and passive solutions.
The new design proposals were: correct orientation according to the wind direction, the increase of the downwind façade opening area and the doubling of the glazed façade 20 cm towards the internal side, in order to realize a Passive Double Skin Façade. This façade would preheat the air in the heating mode and remove the unwanted heat gain during summer, just by a daily and seasonal opening control strategy. Furthermore it would increase the U-value of the façade and improve the thermal comfort by means of lower glazed surface temperature in summer and a higher one in winter.
The Final Result
The results showed a 52% decrease in primary energy heating consumption from 88 to 42 kWh/m2y. With regards to summer the simulation showed that, despite the opposite being expected, the optimum orientation of the building was contrary to the main wind direction. This is because the unwanted solar heat gain will be removed mainly during the non-occupied period.
Furthermore, the introduction of the Double Skin Facade was not able by itself to reduce the internal temperature, but had to be coupled with Cross Ventilation and Night Ventilation to reach comfort levels higher than the normal façade. This was due to the pressure losses introduced with the double glazing and frame. Thus it was important to increase the downwind façade opening area in order to increase the cross ventilation capacity.