Passive House Standard for NZEBs in Warmer Climates

Passive House Standard as an approach to Net-Zero in cooling dominated climates

The Passive House standard is an international concept for high-performance buildings which aims to provide high indoor comfort and good air quality at very low operational costs and energy demand. You can find many Passive House examples with different building designs, shapes, materials, sizes or typologies on the Passive House Database. As of the beginning of this year, there are more than 23.5 Lakh sqm. of certified Passive Houses (PH) around the world. PH concept can be applied to both, new buildings and refurbished buildings.

Passive Houses

The Passive House Institute (PHI) was founded in 1996 by Dr Wolfgang Feist in Germany. PHI has several wings including building certification & consultancy, component certification & consultancy, training, energy modelling tools – designPH & PHPP, research, Passipedia – an online knowledge resource, and knowledge sharing activities through iPHA (International Passive House Association) and International Passive House Conferences.

Naman Sukhija explained why it is important to prioritize energy efficiency over renewables in a building. Further, he explained how the combination of energy efficiency and renewable is promoted with the two classes of the PH standard – Plus & Premium. The PH standard can help buildings reduce their space cooling demand by up to 80%, which makes the standard an effective solution for Net-Zero approach. PH standard helps the building to achieve energy efficiency levels beyond national minimum energy performance standards and compliments those standards.
Passive Houses are versatile and can be adapted to any climate and building type. It prioritizes the building occupants’ health and comfort by proving continuous fresh and clean air. Also, they are economically viable during their lifecycle due to very low operational costs.

Jessica Grove-Smith discussed the difference between two approaches for thermal comfort as per ASHRAE Standard 55. The findings and correlations in the PMV method for air-conditioned spaces indicate that people may tolerate and accept higher temperature in a free-running building but prefer lower temperatures if given the choice to use air conditioning. These lower conditions should, therefore, be our reference for designing buildings. Acknowledging the
relationship between temperature & humidity, the PH standard has limits of 20 °C for heating, 25°C for cooling and specific humidity limit of 12g/kg to ensure thermal comfort, healthy indoors conditions and the structural integrity of the building envelope. This is important so that the buildings can provide resilience against heat waves and future climate conditions.

More and more people aim for cooler conditions and most of them will install and run air conditioning when they can afford it. If buildings are not designed for this, the energy use for cooling will be huge. The webinar showed the success story of the retrofit project of Star Garment Innovation Centre, Sri Lanka. The monitoring data collected by PHI for several projects confirms that the Passive Houses work as expected in the design phase. For a successful project, it is important to have a committed team of experts, reliable design tools and highly efficient components. PHI works to develop the market of components locally by consultation and certification of local components which helps in reducing the investment costs.

Camille Sifferlen explained the strategies required in hot climates for a Passive House. The internal and external loads can be limited with energy-efficient appliances, with insulation, cool colours, high-performance windows, appropriate shading, airtightness and efficient ventilation with heat and/or humidity recovery system, depending on the climate. Camille showed an example of different insulation thickness required in Bhubaneshwar & Bengaluru.

The thickness and type of insulation vary with each climate. It is also important to avoid or minimize thermal bridges in the project. One of the most common thermal bridge can be found at the balcony slabs and it can be avoided by using thermal breaks or having a separate structure for the balcony or a limited number of consoles interrupting the insulation layer. In hot climates, shading and efficient windows are crucial to minimize heat gains. The PH standard requires an airtight envelope to prevent hot & humid air from entering inside through the building envelope. Also, renewal of indoor air is very important because people need fresh air due to various reasons. Whether you should recommend mechanical ventilation or window ventilation depends on the climate and the quality of the outside air. There is no standard approach for every project but it is important to find a cost-effective solution in the early stage of a project by trying different combinations in the PHPP. If after optimising the building envelope and mechanical systems a small cooling demand remains, active cooling will be needed. In that case, it is recommended to use energy-efficient cooling and
dehumidification units. She also showcased the ongoing study for energy-efficient type designs residential buildings in different climates of India. The study is supported by GIZ India on behalf of the Bureau of Energy Efficiency (BEE) and is carried out in collaboration with Ashok B Lall Architects, LEAD Consultancy and Engineering Services and KPMG India.

This webinar was conducted on 12th August 2020.

Jessica Grove-Smith

He is a physicist at the Passive House Institute. Her areas of expertise include energy efficient building solutions in different climate zones, interrelations between efficiency and renewable energies and deep energy efficiency for public indoor swimming pools.

Camille Sifferlen

He is an architect with experience in sustainable building in Spain, China, Australia and Germany. She works in the area of training, as well as building certification and consulting, especially for construction projects in emerging countries with warm climates.

Naman Sukhija

He works in the areas of building consultancy and certification, with a focus on the Passive House market in India.

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