Robert Bosch: Energy-Efficient HVAC Technology Turns a New Building into an Energy Plus Home
A sound energy concept plays an important role when planning a new building. After all, the decisions taken in the planning phase are often binding for decades. Those who opt for efficient technologies are on the right track to saving a lot of energy in the long run. Furthermore, an average new building without special demands made on wall thickness or insulation can be turned into an Energy Plus Home with a positive energy balance, as the following example shows.
General Data
The new building complies with the current German building standard EnEV. The family of four is living on a total floor space of 178 square metres. An annual consumption of 70 kilowatt hours per square metre is assumed for the heating. The reference heating system is a condensing gas boiler. The house in Würzburg (Bavaria, Germany) is oriented to the south; the walls are made of 24 cm concrete plus 12 cm insulation (polyurethane). The roof has a pitch of 30° and offers a usable surface area of 78 square metres for photovoltaics. The family of four has an annual electricity consumption of 4,700 kilowatt hours. The energy required for domestic water heating is 3,800 kilowatt hours per year.
The Energy Plus technology
A++ rated household appliances like the efficient heat pump dryer EcoLogixx 7 S from Bosch contribute considerably to reducing consumption. The power consumption of the dryer is 50 percent less than in energy efficiency class A (limit: 0.48 kWh/kg).
On the southward roof, the photovoltaic modules S_19 from Bosch collect free solar energy. The efficiency is 13.7 percent, the nominal output 225 watts. This means that the modules work very efficiently. The complete roof surface of 78 square metres can be used for the installation of the system.
Energy is lost above all through the wrong type of ventilation. Keeping windows open for extended periods of time is quite expensive, as 50 to 70 percent of the heat is lost. From an energy efficiency point of view, controlled ventilation makes much more sense. The Logavent HRV ventilation from Buderus, a brand of Bosch thermotechnology, achieves an efficiency rating of 91 percent. With one kilowatt hour of electricity, it recovers up to thirty times the equivalent amount of energy. This ventilation provides maximum comfort for the inhabitants, who benefit from the reliable and silent operation of the Logavent HRV. And allergy sufferers can take a deep breath, too, as high-quality filters keep the pollen out.
Another major contribution to the Energy Plus Home is made by the heating system. The family uses the advantages of the Logano SP161 pellet boiler from Buderus. Thanks to optimum combustion, it has an efficiency of up to 93 percent – with very low emissions. As the boiler has an automatic cleaning function for the heat exchanger and the combustion grate, the efficiency remains consistently high and the maintenance costs stay low in the long term. Thanks to the modulating output, the Logano SP161 is an ideal heat source for single-family homes like the one in Würzburg.
The Result
Not all new buildings are the same. By leveraging the potential of energy-efficient technologies consistently, you can turn a standard new building into a genuine energy supplier. In this example, a primary energy surplus of 96 kilowatt hours per square metre and year is generated. The investment of € 56,000 for household appliances, a photovoltaic system, controlled ventilation and pellet boilers breaks even after only ten years – and the energy balance of the house remains positive the entire time. Even with constant energy prices, the appliances save € 5,300 per year in a conservative calculation.
More details on the project are available here.