Villa Neuffen.
All-Electric Since 2016 — Ten Years of Operating Experience.
Frank Hummel’s own operating property: this case study separates the stated operating experience from the 2026 comparison model. What was revolutionary in 2016 can now be reassessed economically. A 500 sqm premium residence with no gas or heat pump, powered by an all-electric system combining PV, infrared heating and storage. The original 2016 model shows a net electricity cost balance of EUR 856 per year. Despite 21% higher consumption from EV charging and the pool, the comparable 2026 model comes to EUR 949 per year.
A Historical Reference. Clear Responsibilities.
Starting Point. Villa Neuffen is presented here as a historical proof of concept from Frank Hummel's own operating context. It is not an HSG client project. This page does not document any involvement by HSG or HUMMEL energize in planning, installation or ongoing operation.
Decision. The 2016 decision is described as the building concept of its time: photovoltaics, infrared heating, heat-recovery ventilation, a domestic-hot-water heat pump and storage. It is not a general recommendation; suitability and design must be assessed for each property.
Roles. The HSG-owned Innovation HUB in Frickenhausen is a separate reference site. There, HUMMEL energize is a legally and entrepreneurially independent specialist partner for its assigned responsibilities. Those roles do not transfer to Villa Neuffen.
Economic Context. Economic figures are read according to their status: the 2016 values are historical values stated in the available assessment, not a metered series disclosed here. The 2026 values are calculated comparison-model scenarios with assumptions about components, consumption, storage and tariff.
Four Building Blocks. One Integrated System.
Villa Neuffen in Baden-Wuerttemberg is a premium single-family home with 500 sqm living space, pool and sauna. In 2016, it was equipped with a radically simple energy concept — no fossil fuels, no heat pump, no underfloor heating.
Photovoltaics
29.68 kWp · 102 Modules
BenQ SunVivo modules on south roof, 29,271 kWh/a generation
Infrared Heating
Vitramo Panels · 26 kW
Room-by-room KNX-controlled, no moving parts, >30 year lifespan
Ventilation with HRV
BluMartin freeAir · >90%
Decentralized ventilation with heat recovery, 8 sensors per unit
Hot Water HP
Stiebel Eltron · COP 3.2
Domestic hot water heat pump, 300L storage
2016: No Gas. No Heat Pump. No Underfloor Heating.
When Villa Neuffen was planned in 2016, the concept was considered bold. Infrared heating in a 500 sqm house with pool? Without a backup system? The industry was skeptical. Today, 10 years later, the operational data shows: The system works — reliably, maintenance-free, and more economically than any alternative.
- No gas connection, no oil tank, no chimney
- No heat pump — direct electricity use via infrared
- No underfloor heating — fast response time through IR radiation
- KfW Efficiency House 55 standard achieved
- Complete KNX building automation with room-by-room control
2016: EUR 856 Net Electricity Cost Balance.
The 2016 assessment shows a net electricity cost balance of EUR 856 at annual consumption of 22,000 kWh. This figure offsets grid electricity costs against revenue from exported solar power; it is therefore not a measure of gross electricity purchasing costs.
Data status · historical stated values: the 2016 figures reproduce the available assessment. This page does not present a continuous, independently verifiable series of meter readings or invoices.
Net electricity cost balance
€856/yr
PV generation
29,271 kWh/a
Total consumption
22,000 kWh/a
Self-sufficiency
48%
Investment
€99,949
Storage (2016)
19 kWh
Ten Years Later: Remodelled on a Comparable Basis.
In 2026, the concept was remodelled using current component prices, 55 kWh of storage and a comparable fixed tariff. Modelled investment falls by 27%, while storage capacity rises from 19 to 55 kWh. Despite 21% higher consumption, the net electricity cost balance is EUR 949 per year versus EUR 856 per year. Source: Villa Neuffen 2026 comparison model.
Data status · calculated scenario: all 2026 amounts, percentages and comparisons rely on the described model and its assumptions. They are not operating readings, offers or a forecast of returns.
Scroll table sideways
| 2016 | 2026 | Delta | |
|---|---|---|---|
| Investment | €99,949 | €72,699 | -27% |
| Storage capacity | 19 kWh | 55 kWh | +190% |
| Storage price/kWh | €1,397 | €480 | -66% |
| PV module price/Wp | €0.67 | €0.18 | -74% |
| Net electricity cost balance/year | €856 | €949 | +11% |
21% More Consumption. 63% Less Grid Electricity.
In the comparison model, annual consumption rises from 22,000 to 26,695 kWh due to EV charging and the pool. At the same time, modelled grid electricity falls from 11,406 to around 4,200 kWh with 55 instead of 19 kWh of storage. After offsetting grid electricity costs against solar export revenue, the net electricity cost balance is EUR 856 per year in the 2016 model and EUR 949 per year in the 2026 fixed-tariff model. These are scenario calculations, not utility bills or guaranteed forecasts.
Data status · assumed tariff comparison: the two cards compare model cases. They establish neither an entitlement to a tariff nor guaranteed self-sufficiency, savings or economic performance.
2016: 19 kWh storage, 22,000 kWh consumption, 11,406 kWh grid electricity, fixed tariff 27 ct/kWh
€856/yr balance
2026: 55 kWh storage, 26,695 kWh consumption, approx. 4,200 kWh grid electricity, fixed tariff 37 ct/kWh
€949/yr balance
Same Technology. Commercially Scaled.
The system logic behind Villa Neuffen has also been proven in a commercial setting. Since 2012, HSG's own site in Frickenhausen has combined infrared heating, photovoltaics and KNX automation and has since been expanded with 270 kWh storage plus AC and 150 kW DC charging. The comparison shows that the core logic scales from residential to commercial sites, subject to site-specific design and economic assessment.
HUMMEL Systemhaus Case StudyTen Years in Operation. Proven in Practice.
Villa Neuffen documents a proof of concept: a fully electric building with infrared heating, photovoltaics and storage can operate economically and reliably over the long term. What was revolutionary in 2016 is a robust ten-year operating reference in 2026.
This conclusion concerns this historical reference and the explicitly separate comparison model. It does not replace a property-specific technical and economic assessment for other buildings.
"We built in 2016 what everyone wants today. Not as an experiment — as a home."
Frank Hummel, Owner & CEO HSG
Your Building. Electric. Economical.
Let us check in a non-binding sparring session how the concept can be transferred to your property — whether residential or commercial.
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