August 2, 2013

High Performance Buildings – Part 1: Has the age of positive energy building come?

During the EU Sustainable Energy Week in Brussels, the EC-Joint Research Centre and ENEA and DYNASTEE-INIVE were the organizers of the event on High Performance Buildings – Design and Evaluation Methodologies taking the place 24-26 June 2013. The presentation by Hans Erhorn from Fraunhofer Institute for Building Physics from Stuttgart started about zero energy buildings to be landmarks in the development systems for future buildings. The vision of a building that produces more energy that uses has come closer with the development of plus energy house or positive energy house.

In the last 30 years, the development of energy-efficient house has taken a huge leap starting from development of energy-saving construction such as solar house, low-energy building, three-liter house, zero-heating energy building and plus-energy house.

The requirements for energy-efficient house extending to building blocks of energy-efficient plus house include a combination of energy efficiency and renewable energy. The methods used are a suitable building design (compact structure, optimum orientation), improving thermal insulation (high-performance windows and insulation systems), optimized work (no thermal bridges, airtight construction and connections), energy-conscious user behavior and comfort, low heating system (short pipe lengths in heating, low energy pumps and fans), and demand controlled heating and ventilation systems along with passive and active renewable systems.

In Germany, the development of new Efficiency House Plus with the E-Mobility is taken the place with the introduction of a new credit system with extended energy performance certificate and loan program. This system offers more economical and practical solution for building companies in Germany to built more solar power in the façade or else, and have higher energy need / higher transmission losses than passive house concept. The most used technologies are PV with batteries, active and passive ventilation resulting in hybrid system, heat pump and also LED lighting.

The Efficiency House Plus needs to extend the design boundaries, i.e. to answer the question what energies can be included in the energy analysis. The extra costs for Efficiency House Plus projects are approximately 200 – 300 EUR/m2 more compared to the passive house concept. These projects also try to take into account the embodied energy in nZEB which needs to be included in the energy calculations.

“The key findings of the Efficiency House Plus projects are that the net heating energy demand of the analyzed houses is in average 25 kWh/(m2.), which is slightly higher than the passive house requirements. All buildings use a floor heating system for emitting the heat with low system temperature in order to increase the performance of a heat pump. Heat generation is mostly realized by electrically driven geothermal heat pumps. For domestic hot water generation are partly covered by solar thermal collectors. All buildings have integrated photovoltaic systems in roof or facades with an average 10 kWpeak output (~ 0.50 m2 per m2 living area). For increasing the share of self-used electricity generated in the building, batteries with a capacity of 2-8 kWh are installed. The monitoring results from previous year show that the buildings generated more energy than needed for their operation; therefore there is a need for re-using this energy.”