Detailed Analysis of Characteristics
Compare space heating characteristics (underfloor, wall, radiators, forced air - ducted & ductless) across comfort, efficiency, cost, and installation, considering Small (S <75m²), Medium (M 75-150m²), and Large (L >150m²) properties, new construction and renovation, and options of space heating subsytems.
Characteristics Assessment Table (S/M/L Property Sizes)
Size Categories:
- S = Small (<75m²)
- M = Medium (75-150m²)
- L = Large (>150m²)
| Characteristic | Air heating - Ductless (Mini-Split) | Air heating - central (Ducted) | Radiator heating - high temperature | Radiator heating - low temperature | Underfloor heating (water) | Wall heating (water) |
|---|---|---|---|---|---|---|
| Heat distribution uniformity | S🟡 M🔴 L🔴 – Harder in large/complex rooms | S🟡 M🟡 L🔴 – Difficulty balancing large duct systems | 🔴 Low — Creates local heat zones. Cold zones, overheating near radiators. | 🟡 Medium — But if there are few radiators, floor area can be cold. | 🟢 High — Optimal vertical distribution | 🟢 High — Similar to underfloor heating. But if walls are blocked by furniture, heat distributes poorly. |
| Thermal comfort | 🟡 Medium (Drafts near unit) | 🟡 Medium — Can create drafts | 🟡 Medium — Has convection flow issues | 🟢 Above average — Has convection flow issues | 🟢 High — Ideal temperature profile, gentle radiant heat, warm floors | 🟢 High — Ideal temperature profile, gentle radiant heat |
| Humidity comfort | 🔴 Low | 🔴 Low — Without air humidifier in system 🟢 High — With humidifier (added cost/complexity) | 🔴 Low — Air dehumidification occurs. Convection flows worsen the problem. | 🟡 Medium | 🟢 High — Thanks to uniform heat distribution and operation at low carrier temperatures. | 🟢 High — Same as underfloor heating |
| Risk of window condensation | 🟡 Medium | 🟡 Medium | 🔴 High — especially with too high radiator temperatures | 🟡 Medium | 🟡 Medium with normal heating | 🟢 Low when placed on wall with windows and normal heating |
| Dust and allergen spread | 🟡 Medium (Moves room air) | 🔴 High (Duct system circulation) | 🟡 Medium | 🟢 Below average | 🟢 Low | 🟢 Low |
| Bacteriological safety | 🟡 Medium (Indoor unit needs cleaning) | 🔴 Low (Ducts can harbor growth) | 🟡 Medium | 🟡 Medium | 🟢 High | 🟢 High |
| Risk of moisture in corners and enclosed wall areas | 🟡 Medium | 🟡 Medium | 🔴 High — especially with poor air circulation | 🟡 Medium — especially with poor air circulation | 🟢 Low | 🟢 Low |
| Noise comfort | 🟡 Medium (Indoor fan noise) | 🔴 Low (System noise, air rush) | 🟢 High | 🟢 High | 🟢 High | 🟢 High |
| Appearance | S🔴 M🔴 L🔴 – More units = worse aesthetics | 🟢 Diffuser face visible 🔴 Without false ceiling - also air ducts and diffuser housings visible | 🟡 Radiators visible 🔴 With exposed piping, pipes also visible | 🔴 Large area radiators visible 🔴 With exposed piping, pipes also visible | 🟢 Not visible | 🟢 Not visible |
| Space usage comfort | S🟡 M🔴 L🔴 – More units = more placement constraints | 🟢 High | 🟡 Medium — Radiators and exposed pipes limit room use | 🔴 Low | 🟢 High | 🟡 Medium — Shouldn’t cover significant part of heated wall with furniture. When drilling walls, must avoid pipes, which are visible with thermal imaging when heating or cooling is on. |
| Reduction in useful room height | 🟢 None | 🔴 High, requires thick air ducts | 🟢 None | 🟢 None | 🟡 Medium for new construction and renovation when screed required — By 5-7+ cm (insulation 3+ cm and 2-4+ cm screed thickening)³ 🔴 High for renovation without screed requirement (rare) — By 10+cm (insulation 3+ cm and 7+ cm screed)³ | 🟢 None |
| Reduction in useful room area | 🟢 None | 🟢 None | 🟠 Yes | 🔴 Yes | 🟢 None | 🟡 By plaster layer about 2 cm |
| Material restrictions | 🟢 None | 🟡 False ceiling to hide ducts | 🟢 None | 🟢 None | 🟡 Floor coverings with high thermal conductivity (ceramics, porcelain stoneware, rocks, concrete) | 🟡 Wall and finishing materials with high thermal conductivity and capacity (brick, concrete, plaster, putty, paint/wallpaper) |
| Void formation | 🟢 None | 🔴 Yes when hiding air ducts and diffuser housings with false ceiling — Extensive voids 🟢 None with exposed installation | 🟢 None | 🟢 None | 🟢 None | 🟢 None |
| Efficiency | 🟢 High — No duct losses | S🟡 M🟡 L🔴 – Duct losses impact larger systems | 🟡 Medium | 🟢 High | 🟢 High — Low-temperature operation mode | 🟢 High — Low-temperature operation mode |
| Installation simplicity | S🟡 M🔴 L🔴 – Multi-zone adds significant complexity | 🔴 Complex — Requires ductwork | 🟢 Simple — Minimum construction work | 🟢 Simple — Minimum construction work | 🟢 Simple for new construction and renovation with new screed layer 🔴 Complex for renovation requiring complicated old screed replacement | 🟢 Simple for new construction. 🟡 Medium for renovation — Requires groove cutting and possibly deepening electrical wiring where crossing pipes |
| Installation cost | S🟡 M🔴 L🔴 – Multi-zone escalates cost | 🔴 High | 🟢 Low | 🟢 Low | 🟡 Medium for new construction and renovation with new screed layer 🔴 High for renovation requiring complicated old screed replacement | 🟢 Low for new construction 🟡 Medium for renovation |
| Materials and equipment cost² | S🟡 M🔴 L🔴 – Multi-zone escalates cost | 🔴 High — Even without boiler room elements | 🟡 Medium | 🔴 High | 🔴 High | 🟡 Medium |
| Service life | 🟡 15-20 years | 🟡 15-20 years | 🟢 30-50 years | 🟢 30-50 years | 🟢 40-50 years. High reliability (pipes in screed, low temp/pressure) | 🟢 40-50 years. High reliability (pipes in plaster, low temp/pressure) |
| Maintenance complexity | S🟡 M🔴 L🔴 – More units = more filters/drains | 🔴 High — Requires regular filter and air duct maintenance | 🟡 Medium — Regular cleaning of radiators and exposed pipes required | 🔴 High — Large radiators | 🟢 None required | 🟢 None required |
| Thermal inertia | 🔴 Low | 🔴 Low | 🔴 Low | 🟡 Medium | 🟢 High | 🟢 High |
| Cooling compatibility¹ | 🟢 Excellent | 🟢 Excellent | 🔴 None | 🟠 Poor¹ — High condensation risk | 🟡 Medium¹ — Medium condensation risk with high humidity | 🟢 Good¹ — Low condensation risk with high humidity |
Explanatory Footnotes
Cooling Compatibility Note: Compatibility ratings (Poor, Medium, Good) assume use in combination with ceiling fans set to upward flow. This mode creates gentle circulation, enhancing cooling distribution and minimizing drafts from chilled surfaces (15-20°C water). Without fans, using these systems for cooling is generally less effective and carries higher condensation risks.
Material and Equipment Costs in Detail: Costs listed exclude boiler room components (heat pump, boiler, primary controls, etc.) unless specified.
Ductless (Mini-Split) Air Heating Costs
- Outdoor unit(s)
- Indoor unit(s)
- Refrigerant line sets
- Condensate drain lines
- Electrical wiring
Total subsystem cost: Medium (single-zone) to High (multi-zone)
Central Ducted Air Heating Costs
- Air duct system
- Fans and diffusers
- False ceiling materials (if hiding ducts)
Total subsystem cost: High
The air heat pump, filtration system, humidifier, and primary control automation are considered part of the boiler room, similar to water heating, and are not included in this subsystem cost. Boiler room equipment costs are high for both air and water heating.
Water Heating Costs (Hydronic)
Comparison of Floor Screed With and Without Underfloor Heating: Floor screed is often installed even without underfloor heating for leveling, strength, or basic insulation. Understanding the differences helps clarify the additional cost attributable to underfloor heating screed requirements.