保温隔热材料指南 (Insulation Materials Guide)
1. Why Insulation Matters in Renovation
Proper insulation reduces energy costs by 20–40%, improves thermal comfort, reduces condensation and mold risk, and provides acoustic benefits. In renovation projects, insulation upgrades are most cost-effective when walls, windows, or roofs are already being opened up.
Key Metrics
| Term | Symbol | Definition | Unit |
|---|---|---|---|
| Thermal Conductivity | λ (lambda) | Heat flow through 1m thickness per 1°C difference | W/(m·K) — lower is better |
| Thermal Resistance | R-value | Thickness / conductivity; resistance to heat flow | m²·K/W — higher is better |
| U-Value | U | Overall heat transfer coefficient of an assembly | W/(m²·K) — lower is better |
| R-Value (US) | R-US | Imperial resistance | ft²·°F·h/BTU |
Conversion
- R-value (metric) = thickness (m) / λ
- R-US ≈ R-metric × 5.678
2. Insulation Material Types
Material Comparison Table
| Material | Chinese Name | λ (W/m·K) | Form | R-value per 50mm | Fire Rating | Cost (per m², 50mm) | Best Use |
|---|---|---|---|---|---|---|---|
| Expanded Polystyrene (EPS) | 膨胀聚苯板 (EPS) | 0.032–0.038 | Rigid board | ~1.3–1.6 | B1 (flame-retardant) | Low | Exterior wall insulation |
| Extruded Polystyrene (XPS) | 挤塑聚苯板 (XPS) | 0.028–0.034 | Rigid board | ~1.5–1.8 | B1/B2 | Low–Mid | Floor, roof, below-grade |
| Rock Wool / Mineral Wool | 岩棉板 | 0.034–0.040 | Board or batt | ~1.25–1.47 | A (non-combustible) | Mid | Fire-rated walls, facades |
| Glass Wool | 玻璃棉 | 0.032–0.044 | Roll / batt | ~1.1–1.56 | A (non-combustible) | Low–Mid | Ceiling, stud wall cavities |
| Polyurethane Foam (PUR/PIR) | 聚氨酯板 | 0.022–0.028 | Rigid board / spray | ~1.8–2.3 | B1/B2 | High | Roof, thin-profile walls |
| Aerogel Blanket | 气凝胶毡 | 0.014–0.020 | Flexible blanket | ~2.5–3.6 | A | Very High | Space-constrained retrofits |
| Phenolic Foam | 酚醛板 | 0.018–0.025 | Rigid board | ~2.0–2.8 | B1 | High | Fire-sensitive applications |
| Reflective Foil (Radiant Barrier) | 铝箔反射隔热膜 | N/A (reflective) | Sheet / roll | ~0.3–0.8 (effective) | Varies | Low | Attic / roof radiant barrier |
3. Wall Insulation (墙体保温)
Exterior Wall Insulation (外保温)
The most effective approach — wraps the entire building envelope.
Common Systems
| System Type | Description | Thickness | Typical R-value | Suitable For |
|---|---|---|---|---|
| EIFS (External Insulation Finish System) | Insulation board + adhesive + mesh + finish coat | 50–120mm | 1.5–4.0 | New construction, major renovation |
| Ventilated Facade (幕墙) | Insulation + air gap + cladding panel | 60–150mm | 1.7–4.5 | Commercial, high-end residential |
| Insulating Render (保温砂浆) | Lightweight insulating plaster | 20–40mm | 0.5–1.0 | Heritage buildings, thin-profile retrofit |
EPS Board Installation Steps
- Clean and level wall surface
- Apply adhesive in dot-and-perimeter pattern (minimum 40% coverage)
- Press boards firmly, staggering joints in brick pattern
- Wait 24 hours for adhesive set
- Install mechanical anchors (6–8 per m², depending on height)
- Apply base coat with embedded fiberglass mesh
- Apply finish coat (textured render or paint)
EPS Board Installation Checklist
- [ ] Surface must be dry, clean, and structurally sound
- [ ] Boards must be cut tightly around openings (no gaps > 2mm)
- [ ] Stagger vertical joints — never align joints at corners
- [ ] Anchor spacing: 6 per m² below 20m height, 8+ above
- [ ] Mesh overlap at joints: minimum 100mm
- [ ] Temperature during installation: 5–35°C
- [ ] Do NOT install in rain or on wet substrate
Interior Wall Insulation (内保温)
Used when exterior insulation is not possible (heritage buildings, apartments, space constraints).
| Material | Recommended Thickness | Notes |
|---|---|---|
| XPS board | 20–40mm | Thin profile, good performance |
| Aerogel blanket | 10–20mm | Premium, space-saving |
| Phenolic board | 20–30mm | Fire-safe, thin |
| Insulating plaster | 15–30mm | DIY-friendly, lower performance |
Warning: Interior insulation creates a cold bridge at floor/ceiling junctions and can cause interstitial condensation. Always install a vapor barrier on the warm side (facing the room).
4. Window Insulation (窗户隔热)
Window U-Values by Configuration
| Window Type | Glass | Frame | U-Value (W/m²·K) | SHGC |
|---|---|---|---|---|
| Single glazed | Clear single pane | Aluminum (no thermal break) | 5.7–6.5 | 0.85 |
| Double glazed | 5+12A+5 clear | Aluminum thermal break | 2.7–3.2 | 0.70 |
| Double glazed | Low-E + argon | Aluminum thermal break | 1.6–2.0 | 0.40 |
| Triple glazed | Low-E + argon x2 | PVC / wood | 0.8–1.2 | 0.35 |
| Double glazed | Low-E + warm edge spacer | Wood-clad aluminum | 1.1–1.4 | 0.38 |
Window Insulation Upgrade Checklist
- [ ] Replace single-glazed windows minimum with double Low-E
- [ ] Verify thermal break on all aluminum frames
- [ ] Check weatherstripping condition; replace worn seals
- [ ] Install window insulation film in winter (temporary)
- [ ] Seal frame-to-wall gap with low-expansion PU foam
- [ ] Apply silicone sealant on exterior perimeter
- [ ] Consider insulated shutters or blinds for summer heat rejection
- [ ] Verify spacer type: warm edge (thermoplastic) outperforms aluminum spacer
Glass Types Explained
| Glass Type | Description | Benefit |
|---|---|---|
| Low-E (低辐射玻璃) | Microscopically thin metallic coating reflects IR | Reduces heat transfer 30–50% |
| Tinted / Reflective | Absorbs or reflects solar radiation | Reduces solar heat gain |
| Laminated | Two panes with PVB interlayer | Safety + acoustic + UV protection |
| Tempered | Heat-strengthened | Safety (shatters into small pieces) |
| Electrochromic / Smart Glass | Electrically switchable tint | Dynamic solar control, expensive |
5. Roof Insulation (屋顶保温)
Roof Insulation Methods
| Method | Description | Material | Thickness | R-value Range |
|---|---|---|---|---|
| Above-deck (inverted) | Insulation above structural deck, under waterproofing | XPS board | 60–120mm | 1.8–3.6 |
| Below-deck (warm roof) | Insulation below deck, between rafters | Mineral wool, PIR board | 100–200mm | 2.5–7.0 |
| Spray foam | Closed-cell PU sprayed on underside | PU foam | 50–100mm | 1.8–3.6 |
| Loose fill (attic) | Blown cellulose or glass wool in attic space | Cellulose, glass wool | 150–300mm | 3.5–8.0 |
| Reflective foil | Radiant barrier under roof covering | Multi-layer foil | N/A | 0.3–0.8 effective |
Recommended Roof R-Values by Climate
| Climate Zone | Minimum Roof R-value (metric) | Equivalent Thickness (Mineral Wool) |
|---|---|---|
| Hot-humid (South China) | 2.0 | ~70mm |
| Mixed / temperate (East China) | 3.0 | ~100mm |
| Cold (North China) | 4.0 | ~130mm |
| Severe cold (Northeast) | 5.0+ | ~170mm+ |
Installation Checklist — Below-Deck Insulation
- [ ] Ensure roof waterproofing is intact before insulating
- [ ] Provide ventilation gap (50mm minimum) between insulation and roof deck
- [ ] Install vapor barrier on warm side (ceiling side)
- [ ] Do NOT compress batt insulation — it loses R-value
- [ ] Seal all penetrations (wires, pipes, light fixtures) through the vapor barrier
- [ ] Use fire-rated insulation (Class A) near chimneys or heat sources
- [ ] Verify insulation does not block soffit/eave ventilation channels
6. Floor Heating Insulation (地暖保温层)
Floor Heating System Layers (bottom to top)
| Layer | Material | Thickness | Purpose |
|---|---|---|---|
| 1. Structural slab | Concrete | 100mm+ | Base structure |
| 2. Waterproofing | SBS membrane or coating | 2–3mm | Moisture barrier (ground floor) |
| 3. Insulation board | XPS or EPS | 20–30mm | Prevent downward heat loss |
| 4. Reflective film | Aluminum foil | 0.2mm | Reflect heat upward |
| 5. Wire mesh | Steel mesh | 2–3mm | Support and protect pipe |
| 6. Heating pipe | PEX-a or PERT | 16–20mm | Heat distribution |
| 7. Backfill / screed | Concrete or anhydrite | 40–50mm above pipe | Thermal mass and surface leveling |
| 8. Floor finish | Tile, wood, etc. | Varies | Final surface |
Insulation Board Requirements
| Property | Minimum Requirement |
|---|---|
| Compressive strength | ≥ 150 kPa (for residential) / ≥ 250 kPa (commercial) |
| Thermal conductivity | ≤ 0.035 W/(m·K) |
| Water absorption | ≤ 1.5% by volume |
| Fire rating | B1 minimum |
| Thickness | 20mm minimum (ground floor: 30mm recommended) |
Floor Heating Insulation Checklist
- [ ] Ground floor: install waterproofing layer before insulation
- [ ] Upper floors: 20mm XPS minimum; 30mm for better efficiency
- [ ] Perimeter: install edge insulation strip (10–15mm) around all walls
- [ ] Reflective film: seams overlapped and taped
- [ ] Pipe spacing: 150–200mm (closer near exterior walls/windows)
- [ ] Pressure test heating pipes before screed pour
- [ ] Screed must cure 21 days before turning on heating
- [ ] Gradual heat-up: increase temperature 5°C per day during first commissioning
7. Fire Safety Considerations
Insulation Material Fire Ratings
| Rating | Description | Approved Materials |
|---|---|---|
| A (Non-combustible) | Will not burn | Rock wool, glass wool, aerogel |
| B1 (Flame-retardant) | Difficult to ignite, self-extinguishing | EPS B1, XPS B1, PIR |
| B2 (Combustible) | Ignites but slow spread | EPS B2, PU foam |
| B3 (Flammable) | No fire resistance | Unmodified polystyrene — banned in building |
Fire Safety Rules
- Buildings above 27m height: exterior insulation must be Class A
- Buildings 24–27m: minimum Class B1 with fire barriers every 2 floors
- Fire barriers: horizontal mineral wool bands at each floor level (300mm minimum height)
- All insulation must be fully covered with fire-rated render or cladding
- Never leave exposed foam insulation on any building interior
8. Condensation and Vapor Control
The Dew Point Rule
When warm, moist indoor air meets a cold surface, condensation occurs. Insulation changes the temperature profile within the wall, and the dew point may shift.
| Scenario | Risk | Solution |
|---|---|---|
| Interior insulation without vapor barrier | High — condensation within wall | Install vapor barrier on warm side |
| Exterior insulation | Low — structure stays warm | No vapor barrier needed typically |
| Roof insulation without ventilation | High — condensation on underside of deck | Provide ventilation gap or use vapor-open insulation |
| Ground floor without waterproofing | Moderate — rising damp through insulation | SBS membrane under insulation |
Vapor Barrier Installation Checklist
- [ ] Use polyethylene sheet (0.2mm minimum) or vapor-retarding membrane
- [ ] Overlap seams by 200mm; seal with vapor barrier tape
- [ ] Seal around all penetrations (outlets, pipes)
- [ ] Continuous — no gaps or tears
- [ ] On warm side of insulation (room side for interior insulation)
- [ ] Verify with blower door test if possible
9. Selection Guide by Renovation Scenario
| Scenario | Recommended Insulation | Thickness | Estimated R-value |
|---|---|---|---|
| Exterior wall (new build) | EPS board B1 | 80mm | 2.4 |
| Exterior wall (retrofit) | EPS board B1 or mineral wool | 60mm | 1.8 |
| Interior wall (space-constrained) | Aerogel blanket or phenolic board | 20mm | 0.8–1.0 |
| Flat roof | XPS inverted roof system | 100mm | 3.0 |
| Pitched roof (between rafters) | Mineral wool batts | 150mm | 4.0 |
| Attic floor | Blown cellulose | 200mm | 5.0 |
| Floor heating (upper floor) | XPS board | 20mm | 0.6 |
| Floor heating (ground floor) | XPS board + waterproofing | 30mm | 0.9 |
| Window upgrade | Double Low-E + thermal break frame | N/A | U-value 1.6–2.0 |
| Pipe insulation (hot water) | Rubber foam tube | 20mm wall | Prevents heat loss and condensation |
| Hot water tank | PU foam or fiberglass wrap | 50mm | Reduces standby losses 50%+ |
10. Brand and Product Recommendations
| Brand | Product Range | Notes |
|---|---|---|
| Knauf (可耐福) | Glass wool, mineral wool, EIFS | Global leader, full system |
| Rockwool (洛科威) | Mineral wool boards and batts | Fire-safe, acoustic benefits |
| Owens Corning | Fiberglass, foam board | Wide availability |
| BASF | PIR/PUR boards, spray foam | Chemical manufacturer, high performance |
| Saint-Gobain (Isover) | Glass wool, mineral wool | European quality |
| Local XPS manufacturers | Various | Verify compressive strength and fire rating on test report |
Purchasing Checklist
- [ ] Request material test report (导热系数, 燃烧等级, 抗压强度)
- [ ] Verify fire rating certificate from accredited lab
- [ ] Check manufacturing date — aged EPS/XPS loses some performance
- [ ] Buy from authorized distributor to avoid counterfeit products
- [ ] For exterior systems, use complete system from one manufacturer (board + adhesive + mesh + render)
- [ ] Retain all product documentation for building inspection records