Renovation vs New-Build: Heat Pump Installation
Renovation vs new-build in heat pump installation means choosing a heat pump system based on the building type. A new-build heat pump installation is planned before construction, while a renovation heat pump installation upgrades an existing heating system. This difference affects the heat pump type, flow temperature, insulation level, radiators or underfloor heating, installation cost, energy efficiency, and grant eligibility. For homeowners, installers, and energy planners, this context is the starting point for selecting the right heat pump and avoiding poor performance.
What Is “Renovation vs New-Build” in Heat Pump Installation?
The term renovation vs new-build describes the two primary structural contexts in which a heat pump system is installed. A new-build is a property constructed from scratch, where the heating system is designed and integrated during the planning phase. A renovation (also called a retrofit) involves replacing or upgrading the heating system in an existing building.
This distinction is the single most important planning variable in any heat pump project. It determines system type, heat distribution method, installation complexity, required building upgrades, energy performance outcomes, and total project cost.
Every heat pump installation begins with one question: Is this a new building or an existing one? The answer shapes every technical and financial decision that follows.
What is the Core Purpose of Distinction between Heat Pump Installation in Renovation vs New-build
The renovation vs new-build classification serves as a diagnostic framework. It allows planners, installers, engineers, and property owners to:
- Select the correct heat pump technology for the building context
- Identify necessary preparatory work (insulation, radiators, pipework)
- Calculate realistic coefficient of performance (COP) and seasonal COP (SCOP)
- Apply the correct subsidy and grant programs (e.g., BEW in Germany, Raus aus Öl und Gas in Austria, GEAK in Switzerland)
- Estimate payback period and return on investment accurately
The classification is not simply administrative. It has direct engineering consequences. A heat pump operating in a poorly insulated renovation building will underperform measurably compared to the same unit in a purpose-built, well-insulated new-build. Ignoring this context is the most common cause of failed heat pump installations.
Why the Renovation vs New-Build Context Matters
The Core Problem
Heat pumps are temperature-sensitive systems. They are most efficient when the required flow temperature (Vorlauftemperatur) of the heating circuit is low — ideally below 45°C. New-builds are typically designed to operate at 30–35°C flow temperatures. Many existing buildings require 60–75°C to heat adequately through their original radiators.
This mismatch — between what the heat pump delivers efficiently and what the building requires — is the central challenge in renovation projects. It does not exist in new-builds designed around heat pump technology from the start.
Regulatory Pressure in DACH Countries
Building renovation and new-build heating standards are increasingly governed by national and EU-level regulation:
- Germany: The Gebäudeenergiegesetz (GEG 2024) requires new heating systems to use at least 65% renewable energy. Heat pumps meet this standard. New-builds must achieve the Effizienzhaus 40 (EH 40) standard from 2023 onward.
- Austria: The Erneuerbare-Wärme-Gesetz (EWG) phases out fossil fuel heating. The Wohnbauförderung varies by Bundesland and often requires heat pump systems in new residential builds.
- Switzerland: The Mustervorschriften der Kantone im Energiebereich (MuKEn 2014) mandate that new heating systems in existing buildings use at least 10% renewable energy. Many cantons go further.
- EU Directive: The revised Energy Performance of Buildings Directive (EPBD 2024) targets net-zero buildings for all new constructions by 2030 and mandates renovation waves for existing stock.
Understanding whether a project is a renovation or new-build determines which regulatory pathway applies, which grants are available, and what minimum performance standards must be met.
Key Features of Each Context
New-Build Heat Pump Installation
| Feature | Detail |
|---|---|
| Planning phase | Heating system is designed before construction begins |
| Insulation standard | High — typically Passivhaus or Effizienzhaus 40/55 |
| Required flow temperature | 30–45°C |
| Heat distribution | Underfloor heating (Flächenheizung) as standard |
| System integration | Heat pump, hot water, ventilation planned together |
| Installation complexity | Low to moderate |
| Grant eligibility | KfW 297/298 (Germany), Wohnbauförderung (Austria) |
| Typical COP/SCOP | 4.0–5.5+ depending on unit and climate zone |
Renovation (Retrofit) Heat Pump Installation
| Feature | Detail |
|---|---|
| Planning phase | Heating system designed around existing building constraints |
| Insulation standard | Variable — often requires upgrading before installation |
| Required flow temperature | 45–65°C (sometimes higher in poorly insulated buildings) |
| Heat distribution | Existing radiators (may need replacing or upsizing) |
| System integration | Heat pump must interface with existing pipework and controls |
| Installation complexity | Moderate to high |
| Grant eligibility | BEW (Germany), Raus aus Öl und Gas (Austria), GEAK Plus (Switzerland) |
| Typical COP/SCOP | 2.5–4.0 depending on building condition and system design |
Detailed Explanation of Key Features
Insulation and the Building Envelope
Definition: The building envelope is the thermal boundary between conditioned interior space and the outside environment. It includes walls, roof, floors, windows, and doors.
Purpose: A well-insulated envelope reduces heat loss. Lower heat loss means the heating system needs to produce less energy, enabling the heat pump to operate at lower flow temperatures.
Benefits: Lower flow temperatures directly increase heat pump efficiency. Every 1°C reduction in flow temperature improves COP by approximately 2–3%.
Practical Application:
- New-builds are constructed to meet current energy standards (e.g., Effizienzhaus 40) before the heat pump is specified.
- Renovation projects must assess current U-values (thermal transmittance) of walls, roofs, and windows before selecting a heat pump. In many cases, insulation upgrades must precede or accompany the heat pump installation.
Recommended U-values for heat pump suitability:
| Building element | Target U-value (W/m²K) |
|---|---|
| External wall | ≤ 0.20 |
| Roof / top floor ceiling | ≤ 0.15 |
| Ground floor / basement ceiling | ≤ 0.25 |
| Windows | ≤ 1.10 |
Heat Distribution System
Definition: The heat distribution system is the network of pipes, emitters, and controls that delivers thermal energy from the heat pump to the living space. Common systems include underfloor heating, wall heating, and radiators.
Purpose: The distribution system determines the minimum flow temperature the heat pump must produce to heat the building adequately. Low-temperature emitters (e.g., underfloor heating) allow the heat pump to operate more efficiently.
Benefits: Purpose-matched distribution systems reduce energy consumption, extend heat pump lifespan, and lower operating costs.
New-Build Context: Underfloor heating (Flächenheizung) is standard in new-builds designed for heat pumps. The large surface area of floor heating emits heat effectively at 30–35°C. This aligns perfectly with heat pump operating characteristics.
Renovation Context: Existing buildings often have panel radiators designed for 70–80°C flow temperatures. These radiators cannot emit enough heat at 45°C to maintain comfort. Renovation projects require one or more of the following:
- Radiator upsizing: Replacing existing radiators with larger models that emit sufficient heat at lower temperatures
- Additional radiators: Installing extra panels to increase total emission surface
- Conversion to underfloor heating: Full or partial conversion, often combined with renovation work
- High-temperature heat pumps: Selecting units that can produce 65°C or higher flow temperatures (with reduced efficiency)
Practical Application: A hydraulic calculation (Heizlastberechnung nach EN 12831) should be performed for every renovation project. This calculation determines the building’s heat demand and whether existing radiators can meet it at lower flow temperatures.
Flow Temperature and COP Relationship
Definition: Flow temperature (Vorlauftemperatur) is the temperature at which water leaves the heat pump and enters the heating circuit. COP (Coefficient of Performance) measures the ratio of heat produced to electrical energy consumed.
Purpose: Understanding the relationship between flow temperature and COP is essential for accurate energy and cost modelling.
COP at different flow temperatures (approximate, at A7/W35 standard conditions):
| Flow temperature | Typical COP (air-source) |
|---|---|
| 35°C | 4.5–5.5 |
| 45°C | 3.5–4.5 |
| 55°C | 2.8–3.5 |
| 65°C | 2.2–2.8 |
Benefits: Designing for the lowest possible flow temperature is the primary lever for maximising heat pump performance in both new-builds and renovations.
Practical Application: In a new-build with underfloor heating and A7/W35 conditions, an air-source heat pump may achieve a SCOP of 4.5. In a renovation with unimproved radiators requiring 60°C flow temperature, the same unit may achieve a SCOP of 2.8. Annual operating costs at the same electricity price would be approximately 60% higher in the renovation scenario without system optimisation.
System Sizing and Heat Load Calculation
Definition: System sizing is the process of selecting a heat pump with the correct thermal output capacity (kW) to meet the building’s maximum heat demand (Heizlast).
Purpose: An undersized heat pump cannot maintain comfort in cold weather. An oversized unit cycles on and off frequently (short-cycling), reducing efficiency and increasing wear.
New-Build Sizing: Heat load is calculated from the building’s specifications: floor area, U-values, air infiltration rates, and climate data. The process follows EN 12831. New-builds have predictable, low heat loads due to their high insulation standards.
Typical heat loads:
- Passivhaus: 10–15 W/m²
- Effizienzhaus 40: 20–30 W/m²
- Effizienzhaus 55: 30–40 W/m²
Renovation Sizing: Renovation buildings have higher and more variable heat loads. Measurement-based methods (e.g., analysis of historical gas or oil consumption) are often used alongside calculation methods to cross-validate sizing.
Typical heat loads in renovation stock:
- Pre-1978 uninsulated building: 80–150 W/m²
- Partially renovated 1980–2000 building: 50–80 W/m²
- Modernised building (post-2000 renovation): 30–55 W/m²
Benefits: Accurate sizing reduces installation risk, improves efficiency, and ensures comfort. Oversizing is a common and costly mistake in renovation projects.
Domestic Hot Water (DHW) Integration
Definition: Domestic hot water (DHW) provision (Warmwasserbereitung) is the process of heating water for taps, showers, and bathrooms using the heat pump system.
Purpose: Heat pumps can produce DHW alongside space heating. System design must account for the higher temperatures required for DHW (minimum 55°C for Legionella prevention) and storage volume.
New-Build Context: DHW systems are designed from scratch. Fresh-water stations, stratified buffer tanks, and heat pump combisystems are planned as integrated units. Anti-Legionella thermal disinfection cycles are programmed into the control system.
Renovation Context: Existing DHW systems (e.g., gas combi-boiler circuits) must be decoupled and integrated with the heat pump. Storage volume requirements are often higher than what existing cylinders provide. A buffer tank or hydraulic separator may be required.
DHW storage sizing guidance:
| Household size | Recommended DHW storage volume |
|---|---|
| 1–2 persons | 150–200 litres |
| 3–4 persons | 200–300 litres |
| 5+ persons | 300–500 litres |
Types and System Models by Context
Heat Pump Types in New-Build Projects
Ground-Source Heat Pump (Erdwärmepumpe / GSHP)
- Source: Geothermal borehole (Erdsondenanlage) or horizontal ground collector (Flächenkollektor)
- Typical SCOP: 4.0–5.5
- Best for: Large plots with stable ground temperatures; high-performance new-builds
- Regulatory note: Borehole drilling requires cantonal or Landratsamt approval in DACH countries
Air-Source Heat Pump (Luftwärmepumpe / ASHP) — Split or Monobloc
- Source: Outdoor air
- Typical SCOP: 3.5–4.5
- Best for: New-builds without space for ground collectors; urban settings
- Note: Performance decreases at outdoor temperatures below -10°C; backup heating may be required in Alpine climates
Water-Source Heat Pump (Grundwasserwärmepumpe)
- Source: Groundwater via extraction and injection wells
- Typical SCOP: 4.5–6.0
- Best for: Locations with suitable groundwater depth and quality
- Regulatory note: Groundwater use requires water rights permit (Wasserrechtsbewilligung in Austria)
Heat Pump Types in Renovation Projects
High-Temperature Air-Source Heat Pump
- Flow temperature: Up to 75°C
- Typical SCOP: 2.5–3.5
- Best for: Buildings with existing high-temperature radiator systems; minimal building modifications required
- Example units: Vaillant aroTHERM plus (75°C variant), Bosch Compress 7800i AW (high-temp version)
Hybrid Heat Pump System (Hybridheizung)
- Combines heat pump with existing gas or oil boiler
- Heat pump covers base load; boiler handles peak demand at extreme temperatures
- Typical SCOP: 3.0–4.0 (system-level)
- Best for: Step-by-step transition from fossil fuels; buildings with high peak heat demand
- Regulatory note: In Germany, hybrid systems may qualify under the GEG 65% renewable rule if the heat pump covers the primary share
Exhaust Air Heat Pump (Abluft-Wärmepumpe)
- Extracts heat from building exhaust ventilation air
- Only suitable for well-insulated, airtight buildings (Passivhaus-standard renovations)
- Typical output: 2–5 kW
- Best for: Highly insulated renovations with mechanical ventilation systems
Brine-to-Water Heat Pump (Sole-Wasser-Wärmepumpe)
- Often installed in renovations where outdoor space allows ground collectors
- Higher initial cost but lower operating cost than air-source
- Best for: Renovation projects with garden space and stable electricity costs
Use Cases
New-Build Use Cases
Use Case 1: Detached single-family home (Einfamilienhaus), Effizienzhaus 40
- Ground-source heat pump with borehole
- Underfloor heating throughout
- Photovoltaic system integrated for self-consumption
- SCOP target: 4.8
- DHW via heat pump with 300-litre stratified tank
Use Case 2: Multi-family residential building (Mehrfamilienhaus)
- Central air-source heat pump with district heating ring
- Individual flat meters for billing
- Centralised DHW production with anti-Legionella programme
- Building management system (BMS) integration
Use Case 3: Passivhaus — Alpine climate (Austria/Switzerland)
- Ground-source heat pump with exhaust air recovery
- Heating demand so low that DHW production dominates system sizing
- Mechanical ventilation with heat recovery (MVHR) as primary comfort system
Renovation Use Cases
Use Case 4: 1970s detached house, partial insulation upgrade
- High-temperature air-source heat pump (up to 65°C)
- Radiator upsizing in key rooms
- Insulation of roof and ground floor
- SCOP target: 3.2
- Phased approach: full insulation in Year 2
Use Case 5: Altbau apartment block, city-centre location (Vienna/Munich/Zurich)
- Hybrid heat pump system replacing gas central boiler
- Existing radiator system retained (upsized in highest-demand rooms)
- Heat pump handles load above -5°C; gas boiler handles extreme cold
- Grant funding via BEW (Germany) or Förderung aus dem Klima- und Energiefonds (Austria)
Use Case 6: Rural farmhouse (Bauernhaus), pre-1945 construction
- Full building energy audit first (GEAK Plus in Switzerland; Energieausweis in Germany/Austria)
- Comprehensive insulation before heat pump specification
- Ground-source system with horizontal collectors in agricultural land
- SCOP target post-renovation: 3.8
Benefits by Context
Benefits of New-Build Heat Pump Installation
- Maximum efficiency from day one: Building and system are designed together. No compromises on flow temperature or heat distribution.
- Lower total cost of ownership: Higher upfront investment in insulation and underfloor heating is offset by decades of lower energy bills.
- Full regulatory compliance: New-builds designed to current standards meet GEG, EWG, and EPBD requirements automatically.
- Simplified grant access: New-build programmes (KfW 297/298) offer attractive terms for energy-efficient construction.
- Integrated renewables: PV systems, battery storage, and heat pumps can be sized and controlled as a single energy system.
- Future-proof: No legacy systems to retrofit. Smart home integration and demand-response control are built in.
Benefits of Renovation Heat Pump Installation
- Decarbonisation of existing stock: The majority of Central European buildings were built before 1980. Retrofitting these buildings is essential for national climate targets.
- Immediate fossil fuel reduction: Even a heat pump with a SCOP of 3.0 reduces primary energy consumption significantly compared to a gas boiler at 0.9 efficiency.
- Grant-funded transition: BEW grants in Germany cover up to 70% of eligible costs. Austrian Wohnbauförderung and Swiss cantonal programmes offer significant subsidies.
- Step-by-step approach: Renovation allows phased improvement — insulation first, heat pump second, PV third — spreading costs over time.
- Rising property value: Energy-efficient buildings command premiums in DACH real estate markets. An EPC upgrade from G to C can increase market value by 15–25% (source: European Parliament Research, 2023).
- Operational independence: Eliminates exposure to gas price volatility, relevant in post-2022 European energy markets.
Selection Criteria: Which Context Applies and What to Do
Step 1 — Establish the Building Context
Answer these questions to classify your project:
| Question | New-Build Signal | Renovation Signal |
|---|---|---|
| Does the building exist? | No — under planning or construction | Yes — currently occupied or recently vacated |
| When was it built? | — | Pre-2000 strongly suggests renovation challenges |
| What is the current energy rating? | — | EPC below C suggests significant work required |
| Is there an existing heating system? | No | Yes — must be assessed and replaced or integrated |
| Is underfloor heating installed? | Planned from scratch | Unlikely — must assess retrofit feasibility |
Step 2 — Conduct an Energy Audit
For renovation projects, an energy audit is not optional — it is a prerequisite for accurate system design and grant eligibility.
Recommended audit standards:
- Germany: Energieberatung by a zugelassener Energieberater (BAFA-listed); Gebäudeenergieausweis (Bedarfsausweis)
- Austria: Energieausweis (OIB-Richtlinie 6); thermografische Untersuchung for older buildings
- Switzerland: GEAK (Gebäudeenergieausweis der Kantone); GEAK Plus for investment planning
- EU standard: EN ISO 52000 series for building energy performance assessment
The audit establishes:
- Current heat load (kW)
- Annual energy demand (kWh/year)
- Envelope U-values
- Current system efficiency
- Recommended measures in priority order
Step 3 — Select the Heat Pump Type
Use the following decision matrix:
For New-Builds:
| Condition | Recommended System |
|---|---|
| Plot with space for borehole | Ground-source (GSHP) with underfloor heating |
| Urban plot, no ground access | Air-source monobloc or split with underfloor heating |
| Groundwater at accessible depth | Water-source heat pump |
| Passivhaus standard | Exhaust air heat pump or compact ventilation unit |
For Renovations:
| Condition | Recommended System |
|---|---|
| Existing radiators, no insulation upgrade | High-temperature air-source heat pump (≥65°C) |
| Partial insulation, radiators upgraded | Standard air-source heat pump (45–55°C) |
| Full insulation upgrade planned | Ground-source or standard air-source (35–45°C) |
| Phased transition from gas boiler | Hybrid heat pump system |
| Well-insulated Altbau, MVHR system | Exhaust air heat pump |
Step 4 — Confirm Financial Viability
Calculate the total project cost, including:
- Heat pump unit and installation
- Required building envelope improvements
- Heat distribution system changes (radiator replacement, underfloor heating)
- DHW storage and controls
- Electrical upgrades (three-phase supply if required)
- Minus: applicable grants and subsidies
Key grant programmes in DACH (as of 2024–2025):
| Country | Programme | Coverage |
|---|---|---|
| Germany | Bundesförderung für effiziente Gebäude (BEG / BEW) | Up to 70% of eligible costs for renovation |
| Germany | KfW 297/298 | New-build energy-efficient construction loans |
| Austria | Raus aus Öl und Gas (Bundesförderung) | Up to €7,500 flat grant + Landesförderung |
| Austria | Sanierungsoffensive | Up to 50% of insulation costs |
| Switzerland | Gebäudeprogramm (EnAW) | Cantonal co-funding for insulation and heat pumps |
| EU | Renewable Energy Directive (RED III) | Framework for national programmes |
Note: Grant amounts and conditions change. Always verify current terms at official national or cantonal programme websites.
Comparison: Renovation vs New-Build at a Glance
| Criterion | New-Build | Renovation |
|---|---|---|
| Planning complexity | Lower (clean-sheet design) | Higher (constraints from existing structure) |
| System efficiency (SCOP) | 4.0–5.5 | 2.5–4.0 (before upgrades); 3.5–4.5 (after upgrades) |
| Installation cost | Moderate (integrated planning) | Moderate to high (preparatory work required) |
| Grant landscape | New-build efficiency programmes | Renovation and decarbonisation grants |
| Time to installation | After build completion | 2–12 months including preparatory works |
| CO₂ reduction potential | High — fossil-free from day one | High — especially when combined with insulation |
| Radiator replacement risk | None | Significant — major cost driver |
| Regulatory compliance complexity | Straightforward | Variable — depends on building age and condition |
| Property value impact | Built-in (A-rated from start) | Significant uplift when EPC improves |
| Market relevance (DACH) | Growing — but majority of stock is renovation | Critical — 80%+ of existing EU buildings need renovation |
Integration with Other Systems
Photovoltaic (PV) and Battery Storage
Heat pumps and PV systems are the primary residential energy pairing in DACH markets.
New-Build: PV and heat pump are sized together. Smart energy management systems (e.g., SMA Energy System Home, Loxone, Fronius Symo GEN24) coordinate heat pump operation with solar production. Heat pump runs preferentially during PV surplus hours, reducing grid electricity demand.
Renovation: PV integration is possible but requires analysis of available roof area, grid connection capacity, and existing electrical installation. Retro-fitting smart energy management is achievable but adds cost.
Key integration benefit: Self-consumption of PV electricity in heat pump operation can reduce effective electricity cost to 5–8 ct/kWh (versus 25–35 ct/kWh grid tariff in DACH), dramatically improving operating economics.
Mechanical Ventilation with Heat Recovery (MVHR / Lüftungsanlage mit Wärmerückgewinnung)
Definition: MVHR systems extract stale air from the building, recover its heat through a heat exchanger, and supply fresh conditioned air. Heat recovery efficiency reaches 80–90%.
New-Build: MVHR is standard in Passivhaus and Effizienzhaus 40 new-builds. Reduces the heat load that the heat pump must cover. In very low-energy buildings, MVHR may be the primary heat delivery mechanism, with the heat pump serving primarily for DHW.
Renovation: MVHR retrofit is technically feasible but architecturally disruptive (ductwork installation). It is most practical in complete renovation projects. Decentralised ventilation units (Einzel-Lüftungsgeräte) offer a lower-disruption alternative.
Smart Controls and Building Automation
Definition: Smart control systems manage heat pump operation based on building occupancy, weather data, energy prices, and grid signals.
New-Build: Controls are specified and installed as part of the original system design. Integration with KNX, Modbus, or proprietary bus systems is straightforward.
Renovation: Existing heating controls must be assessed for compatibility. Many older systems use simple on/off thermostats incompatible with modern heat pump control logic. Upgrade to weather-compensated control (außentemperaturgeführte Regelung) is typically required.
Key regulatory trend: Dynamic electricity tariffs and demand-response programmes are expanding across DACH markets. Heat pumps with smart control can operate at lowest-tariff periods, further improving economics.
Thermal Storage (Buffer Tanks and Latent Storage)
Definition: Thermal storage systems store excess heat produced by the heat pump for later use, reducing on/off cycling and improving system stability.
New-Build: Buffer tanks are sized and positioned during design phase. Integration with DHW cylinders and hydraulic separators is straightforward.
Renovation: Buffer tanks are frequently required in renovation projects where existing pipework creates hydraulic imbalances. They also allow the heat pump to operate during lower-tariff electricity periods and store heat for peak demand.
Typical buffer tank volumes:
| Building size | Recommended buffer volume |
|---|---|
| Up to 150 m² | 100–200 litres |
| 150–250 m² | 200–400 litres |
| 250 m²+ or multi-family | 400–1,000+ litres |
The Decision Framework
The renovation vs new-build distinction is not a minor administrative classification. It is the foundational context that determines system type, efficiency potential, cost structure, grant eligibility, and installation approach for every heat pump project.
If you are planning a new-build: Design the heat pump system during the architectural planning phase. Specify underfloor heating, target the lowest possible flow temperature, and integrate PV and MVHR from the start. Engage a certified energy consultant (Energieberater) and apply for new-build efficiency grants before construction begins.
If you are renovating: Begin with a certified energy audit (GEAK Plus, Energieausweis Bedarfsausweis, or equivalent). Prioritise envelope improvements. Select a heat pump type matched to the building’s current and projected post-renovation heat demand. Plan for the full system — distribution, DHW, storage, and controls — not just the heat pump unit. Apply for renovation grants early, as many programmes operate on annual budgets.
In both contexts, a heat pump installed with proper planning, accurate sizing, and compatible distribution delivers measurable reductions in energy cost, carbon emissions, and fossil fuel dependency — aligned with both household economics and the regulatory direction of travel across Austria, Germany, Switzerland, and the broader European Union.
