Economics Basics

Energy-efficiency decisions are investment decisions. These are the financial methods behind our economics tools.

Financing & refinancing

Loans are modelled as annuities: the monthly instalment follows from principal, interest rate and repayment rate; subsidised KfW loans additionally carry repayment grants that reduce the outstanding debt. The refinancing tool compares your current loan against a new conditions scenario. → Financing, Refinancing

Renovation economics

A renovation pays off through saved energy cost. We compare the building before and after the measures — energy demand, CO₂ and annual cost — and set the investment against the savings over the observation period, including subsidies. → Renovation Economics, Affordability Check

Heating system comparison & CO₂

Heating technologies are compared on full cost (investment, energy, maintenance) and on emissions using energy-carrier emission factors, including the rising national CO₂ price on fossil fuels. → CO₂ Comparison, CO₂ Footprint

Photovoltaics

PV economics follow a multi-year cash-flow model: yield degradation, self-consumption vs. feed-in remuneration, electricity price escalation and optional battery storage lead to amortisation year and return on equity. → PV Sizing & Yield

Construction costs & valuation

Construction costs are structured along DIN 276 cost groups with published benchmark values; market valuation uses the German standard approaches (asset, income and comparison value). → Construction Costs, Market Valuation