KNX Hackathon Finalist: - EisBaer Software PV Manager and KNX Reduce Household Energy Costs by 80%

LOCAL+ is an initiative involving architectural students from Aachen University of Applied Sciences. Its design challenge was to develop a building that produces excess energy through innovative and forward-looking systems: a so-called plus-energy house that is almost self-sufficient.

The team designed a building that has communal cooking, laundry and garden facilities, as well as four floors, each housing up to three residents. Each resident has their own movable private unit, called a CUBE, that includes a fold-up bed, wardrobe and desk. A demonstration building, comprising the communal cooking and laundry space, plus one living floor, can be visited in Wuppertal, Germany.

To start with, a central hydrogen system, interacting with other components, was specified as the main source of energy, promising up to 65% self-sufficiency. Other components include an underground ice store, PVT collectors and a heat pump. In practice, the hydrogen system was dispensed with due to a short service life, and the ice storage facility was reduced in size due to underground construction constraints.

Apart from these site-related limitations, the system was implemented in line with the plans and uses KNX devices connected via KNX IP Secure to the EisBaer Software PV Manager. In this project, EisBaer software provides the overall control solution for all of the services, including the HVAC, water temperature and energy management.

To generate electricity, PVT modules were installed on the roof and south-west facade of the building, with an output of 18.5kWp and 9kWp respectively. The electricity produced is delivered directly to the mains system during the day, on demand, with excess being stored in a battery for use during the night. Excess energy is also used to run home appliances during the day.

Users have the flexibility to instruct the system to prioritise using the cheapest energy grid, maximise solar power usage, or find a balance between the two. For instance, if an appliance, such as a heat pump, has a minimum required runtime, this constraint is factored into the scheduling process. Additionally, the software can divide the energy load into morning and afternoon segments, much like a battery storage system, allowing for optimised energy usage across the day.

Users always retain the ability to interact with the system, either through direct instructions or preferences. For example, a user might prompt the system to begin the washing cycle within a specific timeframe. The PV Manager would then evaluate solar generation patterns and energy prices to identify the most optimal time to initiate the task. In cases where immediate action is required, users can request to start an appliance 'now'. The system then promptly restructures the existing schedule to accommodate this request while still considering solar availability and energy costs.

Scenario 2: With Energy Management

Using the EisBaer Software PV Manager to schedule the washing machine and dishwasher during times of high solar generation and periods when the energy prices are 20% lower, the savings and costs are as follows:

Savings per day: €0.19/kWh x 0.20 = €0.038/kWh.

For 4320kWh/year: €0.038/kWh x 4320kWh = €164.16

For 6720kWh/year: €0.038/kWh x 6720kWh = €255.36

Total Savings with Energy Management:

For 4320kWh/year: €820.80 (Without Energy Management) - €164.16 (With Energy Management) = €656.64.

For 6720kWh/year: €1276.80 (Without Energy Management) - €255.36 (With Energy Management) = €1021.44.