<\/span><\/h2>\nThe term renovation vs new-build<\/strong> describes the two primary structural contexts in which a heat pump system is installed. A new-build<\/strong> is a property constructed from scratch, where the heating system is designed and integrated during the planning phase. A renovation<\/strong> (also called a retrofit) involves replacing or upgrading the heating system in an existing building.<\/p>\nThis 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.<\/p>\n
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.<\/p>\n
<\/span>What is the Core Purpose of Distinction between Heat Pump Installation in Renovation vs New-build<\/span><\/h2>\nThe renovation vs new-build classification serves as a diagnostic framework<\/strong>. It allows planners, installers, engineers, and property owners to:<\/p>\n\n- Select the correct heat pump technology for the building context<\/li>\n
- Identify necessary preparatory work (insulation, radiators, pipework)<\/li>\n
- Calculate realistic coefficient of performance (COP) and seasonal COP (SCOP)<\/li>\n
- Apply the correct subsidy and grant programs (e.g., BEW in Germany, Raus aus \u00d6l und Gas in Austria, GEAK in Switzerland)<\/li>\n
- Estimate payback period and return on investment accurately<\/li>\n<\/ul>\n
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.<\/p>\n
<\/span>Why the Renovation vs New-Build Context Matters<\/span><\/h2>\nThe Core Problem<\/h3>\n
Heat pumps are temperature-sensitive systems. They are most efficient when the required flow temperature<\/strong> (Vorlauftemperatur) of the heating circuit is low \u2014 ideally below 45\u00b0C. New-builds are typically designed to operate at 30\u201335\u00b0C flow temperatures. Many existing buildings require 60\u201375\u00b0C to heat adequately through their original radiators.<\/p>\nThis mismatch \u2014 between what the heat pump delivers efficiently and what the building requires \u2014 is the central challenge in renovation projects. It does not exist in new-builds designed around heat pump technology from the start.<\/p>\n
Regulatory Pressure in DACH Countries<\/h3>\n
Building renovation and new-build heating standards are increasingly governed by national and EU-level regulation:<\/p>\n
\n- Germany:<\/strong> The Geb\u00e4udeenergiegesetz (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.<\/li>\n
- Austria:<\/strong> The Erneuerbare-W\u00e4rme-Gesetz (EWG) phases out fossil fuel heating. The Wohnbauf\u00f6rderung varies by Bundesland and often requires heat pump systems in new residential builds.<\/li>\n
- Switzerland:<\/strong> 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.<\/li>\n
- EU Directive:<\/strong> 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.<\/li>\n<\/ul>\n
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.<\/p>\n
<\/span>Key Features of Each Context<\/span><\/h2>\nNew-Build Heat Pump Installation<\/h3>\n<\/div>\n\n
\n\n\n| Feature<\/th>\n | Detail<\/th>\n<\/tr>\n<\/thead>\n |
\n\n| Planning phase<\/td>\n | Heating system is designed before construction begins<\/td>\n<\/tr>\n |
\n| Insulation standard<\/td>\n | High \u2014 typically Passivhaus or Effizienzhaus 40\/55<\/td>\n<\/tr>\n |
\n| Required flow temperature<\/td>\n | 30\u201345\u00b0C<\/td>\n<\/tr>\n |
\n| Heat distribution<\/td>\n | Underfloor heating (Fl\u00e4chenheizung) as standard<\/td>\n<\/tr>\n |
\n| System integration<\/td>\n | Heat pump, hot water, ventilation planned together<\/td>\n<\/tr>\n |
\n| Installation complexity<\/td>\n | Low to moderate<\/td>\n<\/tr>\n |
\n| Grant eligibility<\/td>\n | KfW 297\/298 (Germany), Wohnbauf\u00f6rderung (Austria)<\/td>\n<\/tr>\n |
\n| Typical COP\/SCOP<\/td>\n | 4.0\u20135.5+ depending on unit and climate zone<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nRenovation (Retrofit) Heat Pump Installation<\/h3>\n<\/div>\n\n \n\n\n| Feature<\/th>\n | Detail<\/th>\n<\/tr>\n<\/thead>\n | \n\n| Planning phase<\/td>\n | Heating system designed around existing building constraints<\/td>\n<\/tr>\n | \n| Insulation standard<\/td>\n | Variable \u2014 often requires upgrading before installation<\/td>\n<\/tr>\n | \n| Required flow temperature<\/td>\n | 45\u201365\u00b0C (sometimes higher in poorly insulated buildings)<\/td>\n<\/tr>\n | \n| Heat distribution<\/td>\n | Existing radiators (may need replacing or upsizing)<\/td>\n<\/tr>\n | \n| System integration<\/td>\n | Heat pump must interface with existing pipework and controls<\/td>\n<\/tr>\n | \n| Installation complexity<\/td>\n | Moderate to high<\/td>\n<\/tr>\n | \n| Grant eligibility<\/td>\n | BEW (Germany), Raus aus \u00d6l und Gas (Austria), GEAK Plus (Switzerland)<\/td>\n<\/tr>\n | \n| Typical COP\/SCOP<\/td>\n | 2.5\u20134.0 depending on building condition and system design<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/span>Detailed Explanation of Key Features<\/span><\/h2>\nInsulation and the Building Envelope<\/h3>\nDefinition:<\/strong> The building envelope is the thermal boundary between conditioned interior space and the outside environment. It includes walls, roof, floors, windows, and doors.<\/p>\nPurpose:<\/strong> 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.<\/p>\nBenefits:<\/strong> Lower flow temperatures directly increase heat pump efficiency. Every 1\u00b0C reduction in flow temperature improves COP by approximately 2\u20133%.<\/p>\nPractical Application:<\/strong><\/p>\n\n- New-builds are constructed to meet current energy standards (e.g., Effizienzhaus 40) before the heat pump is specified.<\/li>\n
- 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.<\/li>\n<\/ul>\n
Recommended U-values for heat pump suitability:<\/strong><\/p>\n<\/div>\n\n \n\n\n| Building element<\/th>\n | Target U-value (W\/m\u00b2K)<\/th>\n<\/tr>\n<\/thead>\n | \n\n| External wall<\/td>\n | \u2264 0.20<\/td>\n<\/tr>\n | \n| Roof \/ top floor ceiling<\/td>\n | \u2264 0.15<\/td>\n<\/tr>\n | \n| Ground floor \/ basement ceiling<\/td>\n | \u2264 0.25<\/td>\n<\/tr>\n | \n| Windows<\/td>\n | \u2264 1.10<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nHeat Distribution System<\/h3>\nDefinition:<\/strong> 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.<\/p>\nPurpose:<\/strong> 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.<\/p>\nBenefits:<\/strong> Purpose-matched distribution systems reduce energy consumption, extend heat pump lifespan, and lower operating costs.<\/p>\nNew-Build Context:<\/strong> Underfloor heating (Fl\u00e4chenheizung) is standard in new-builds designed for heat pumps. The large surface area of floor heating emits heat effectively at 30\u201335\u00b0C. This aligns perfectly with heat pump operating characteristics.<\/p>\nRenovation Context:<\/strong> Existing buildings often have panel radiators designed for 70\u201380\u00b0C flow temperatures. These radiators cannot emit enough heat at 45\u00b0C to maintain comfort. Renovation projects require one or more of the following:<\/p>\n\n- Radiator upsizing:<\/strong> Replacing existing radiators with larger models that emit sufficient heat at lower temperatures<\/li>\n
- Additional radiators:<\/strong> Installing extra panels to increase total emission surface<\/li>\n
- Conversion to underfloor heating:<\/strong> Full or partial conversion, often combined with renovation work<\/li>\n
- High-temperature heat pumps:<\/strong> Selecting units that can produce 65\u00b0C or higher flow temperatures (with reduced efficiency)<\/li>\n<\/ul>\n
Practical Application:<\/strong> 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.<\/p>\nFlow Temperature and COP Relationship<\/h3>\nDefinition:<\/strong> 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.<\/p>\nPurpose:<\/strong> Understanding the relationship between flow temperature and COP is essential for accurate energy and cost modelling.<\/p>\nCOP at different flow temperatures (approximate, at A7\/W35 standard conditions):<\/strong><\/p>\n<\/div>\n\n \n\n\n| Flow temperature<\/th>\n | Typical COP (air-source)<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 35\u00b0C<\/td>\n | 4.5\u20135.5<\/td>\n<\/tr>\n | \n| 45\u00b0C<\/td>\n | 3.5\u20134.5<\/td>\n<\/tr>\n | \n| 55\u00b0C<\/td>\n | 2.8\u20133.5<\/td>\n<\/tr>\n | \n| 65\u00b0C<\/td>\n | 2.2\u20132.8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nBenefits:<\/strong> Designing for the lowest possible flow temperature is the primary lever for maximising heat pump performance in both new-builds and renovations.<\/p>\nPractical Application:<\/strong> 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\u00b0C 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.<\/p>\nSystem Sizing and Heat Load Calculation<\/h3>\nDefinition:<\/strong> 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).<\/p>\nPurpose:<\/strong> 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.<\/p>\nNew-Build Sizing:<\/strong> 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.<\/p>\nTypical heat loads:<\/p>\n \n- Passivhaus: 10\u201315 W\/m\u00b2<\/li>\n
- Effizienzhaus 40: 20\u201330 W\/m\u00b2<\/li>\n
- Effizienzhaus 55: 30\u201340 W\/m\u00b2<\/li>\n<\/ul>\n
Renovation Sizing:<\/strong> 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.<\/p>\nTypical heat loads in renovation stock:<\/p>\n \n- Pre-1978 uninsulated building: 80\u2013150 W\/m\u00b2<\/li>\n
- Partially renovated 1980\u20132000 building: 50\u201380 W\/m\u00b2<\/li>\n
- Modernised building (post-2000 renovation): 30\u201355 W\/m\u00b2<\/li>\n<\/ul>\n
Benefits:<\/strong> Accurate sizing reduces installation risk, improves efficiency, and ensures comfort. Oversizing is a common and costly mistake in renovation projects.<\/p>\nDomestic Hot Water (DHW) Integration<\/h3>\nDefinition:<\/strong> Domestic hot water (DHW) provision (Warmwasserbereitung) is the process of heating water for taps, showers, and bathrooms using the heat pump system.<\/p>\nPurpose:<\/strong> Heat pumps can produce DHW alongside space heating. System design must account for the higher temperatures required for DHW (minimum 55\u00b0C for Legionella prevention) and storage volume.<\/p>\nNew-Build Context:<\/strong> 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.<\/p>\nRenovation Context:<\/strong> 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.<\/p>\nDHW storage sizing guidance:<\/strong><\/p>\n<\/div>\n\n \n\n\n| Household size<\/th>\n | Recommended DHW storage volume<\/th>\n<\/tr>\n<\/thead>\n | \n\n| 1\u20132 persons<\/td>\n | 150\u2013200 litres<\/td>\n<\/tr>\n | \n| 3\u20134 persons<\/td>\n | 200\u2013300 litres<\/td>\n<\/tr>\n | \n| 5+ persons<\/td>\n | 300\u2013500 litres<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/span>Types and System Models by Context<\/span><\/h2>\nHeat Pump Types in New-Build Projects<\/h3>\nGround-Source Heat Pump (Erdw\u00e4rmepumpe \/ GSHP)<\/h4>\n\n- Source: Geothermal borehole (Erdsondenanlage) or horizontal ground collector (Fl\u00e4chenkollektor)<\/li>\n
- Typical SCOP: 4.0\u20135.5<\/li>\n
- Best for: Large plots with stable ground temperatures; high-performance new-builds<\/li>\n
- Regulatory note: Borehole drilling requires cantonal or Landratsamt approval in DACH countries<\/li>\n<\/ul>\n
Air-Source Heat Pump (Luftw\u00e4rmepumpe \/ ASHP) \u2014 Split or Monobloc<\/h4>\n\n- Source: Outdoor air<\/li>\n
- Typical SCOP: 3.5\u20134.5<\/li>\n
- Best for: New-builds without space for ground collectors; urban settings<\/li>\n
- Note: Performance decreases at outdoor temperatures below -10\u00b0C; backup heating may be required in Alpine climates<\/li>\n<\/ul>\n
Water-Source Heat Pump (Grundwasserw\u00e4rmepumpe)<\/h4>\n\n- Source: Groundwater via extraction and injection wells<\/li>\n
- Typical SCOP: 4.5\u20136.0<\/li>\n
- Best for: Locations with suitable groundwater depth and quality<\/li>\n
- Regulatory note: Groundwater use requires water rights permit (Wasserrechtsbewilligung in Austria)<\/li>\n<\/ul>\n
Heat Pump Types in Renovation Projects<\/h3>\nHigh-Temperature Air-Source Heat Pump<\/h4>\n\n- Flow temperature: Up to 75\u00b0C<\/li>\n
- Typical SCOP: 2.5\u20133.5<\/li>\n
- Best for: Buildings with existing high-temperature radiator systems; minimal building modifications required<\/li>\n
- Example units: Vaillant aroTHERM plus (75\u00b0C variant), Bosch Compress 7800i AW (high-temp version)<\/li>\n<\/ul>\n
Hybrid Heat Pump System (Hybridheizung)<\/h4>\n\n- Combines heat pump with existing gas or oil boiler<\/li>\n
- Heat pump covers base load; boiler handles peak demand at extreme temperatures<\/li>\n
- Typical SCOP: 3.0\u20134.0 (system-level)<\/li>\n
- Best for: Step-by-step transition from fossil fuels; buildings with high peak heat demand<\/li>\n
- Regulatory note: In Germany, hybrid systems may qualify under the GEG 65% renewable rule if the heat pump covers the primary share<\/li>\n<\/ul>\n
Exhaust Air Heat Pump (Abluft-W\u00e4rmepumpe)<\/h4>\n\n- Extracts heat from building exhaust ventilation air<\/li>\n
- Only suitable for well-insulated, airtight buildings (Passivhaus-standard renovations)<\/li>\n
- Typical output: 2\u20135 kW<\/li>\n
- Best for: Highly insulated renovations with mechanical ventilation systems<\/li>\n<\/ul>\n
Brine-to-Water Heat Pump (Sole-Wasser-W\u00e4rmepumpe)<\/h4>\n\n- Often installed in renovations where outdoor space allows ground collectors<\/li>\n
- Higher initial cost but lower operating cost than air-source<\/li>\n
- Best for: Renovation projects with garden space and stable electricity costs<\/li>\n<\/ul>\n
<\/span>Use Cases<\/span><\/h2>\nNew-Build Use Cases<\/h3>\nUse Case 1: Detached single-family home (Einfamilienhaus), Effizienzhaus 40<\/h4>\n\n- Ground-source heat pump with borehole<\/li>\n
- Underfloor heating throughout<\/li>\n
- Photovoltaic system integrated for self-consumption<\/li>\n
- SCOP target: 4.8<\/li>\n
- DHW via heat pump with 300-litre stratified tank<\/li>\n<\/ul>\n
Use Case 2: Multi-family residential building (Mehrfamilienhaus)<\/h4>\n\n- Central air-source heat pump with district heating ring<\/li>\n
- Individual flat meters for billing<\/li>\n
- Centralised DHW production with anti-Legionella programme<\/li>\n
- Building management system (BMS) integration<\/li>\n<\/ul>\n
Use Case 3: Passivhaus \u2014 Alpine climate (Austria\/Switzerland)<\/h4>\n\n- Ground-source heat pump with exhaust air recovery<\/li>\n
- Heating demand so low that DHW production dominates system sizing<\/li>\n
- Mechanical ventilation with heat recovery (MVHR) as primary comfort system<\/li>\n<\/ul>\n
Renovation Use Cases<\/h3>\nUse Case 4: 1970s detached house, partial insulation upgrade<\/h4>\n | | | | |