SBM-2008: The Standard of Building Biology Testing Methods
Complete guide to the SBM-2008 standard — threshold values for EMF, RF radiation, indoor air quality, and more. The building biology precautionary framework explained.
The SBM-2008 is the Standard of Building Biology Testing Methods, 2008 revision, the core technical document of the building biology discipline. Developed by the Institut für Baubiologie + Nachhaltigkeit (IBN) in Germany and adopted by the International Institute for Building-Biology & Ecology (IIBE), it provides specific measurement thresholds for electromagnetic fields, indoor air quality, thermal comfort, acoustics, and radioactivity in residential environments.
Unlike government exposure limits, which are set to prevent acute thermal injury from radiation or immediate chemical harm, the SBM-2008 thresholds are precautionary. They are based on the principle that long-term, low-level exposure to building-related stressors should be minimised, particularly in sleeping areas where the body does its most critical repair work.
How the Standard Works
The SBM-2008 organises every parameter into four concern levels, colour-coded for easy interpretation:
- No Concern, below the precautionary threshold; no remediation required
- Slight Concern, low-level exposure; remediation recommended where easily achieved
- Severe Concern, significant exposure; remediation strongly recommended
- Extreme Concern, high exposure; remediation required as a priority
The standard is applied by certified building biology consultants using calibrated instruments. Measurements are taken in occupied rooms, especially bedrooms, under sleeping conditions (devices in their normal nighttime state, occupants present, WiFi on or off as it would be overnight).
AC Electric Fields
AC electric fields are produced by voltage in electrical wiring, even when no current is flowing, meaning unloaded wires behind bedroom walls still emit electric fields throughout the night. The SBM-2008 measures these in two ways: field strength (V/m) and body voltage (mV), the latter being a direct measure of how much the field induces in the human body.
| Concern Level | Field Strength (V/m) | Body Voltage (mV) |
|---|---|---|
| No Concern | < 1 | < 10 |
| Slight Concern | 1 – 5 | 10 – 100 |
| Severe Concern | 5 – 50 | 100 – 1,000 |
| Extreme Concern | > 50 | > 1,000 |
The most common remediation for elevated AC electric fields is a demand switch (automatic load disconnection switch) on the bedroom circuit, which cuts voltage in the wiring when no current is drawn, eliminating the field entirely during sleep. See the electric field guide for full remediation options.
AC Magnetic Fields
AC magnetic fields require current to flow, they come from operating appliances, transformers, and wiring with current running through it. Unlike electric fields, magnetic fields pass through almost all building materials and cannot be blocked by a demand switch. Sources include the power grid, nearby transformers, current imbalances in wiring, and appliances such as refrigerators, clock radios, and electric blankets.
| Concern Level | Magnetic Flux Density |
|---|---|
| No Concern | < 20 nT (0.2 mG) |
| Slight Concern | 20 – 100 nT (0.2 – 1 mG) |
| Severe Concern | 100 – 500 nT (1 – 5 mG) |
| Extreme Concern | > 500 nT (> 5 mG) |
The SBM-2008 "No Concern" threshold of 20 nT is approximately 2,500 times more stringent than the ICNIRP public limit of 50,000 nT (50 µT). The precautionary basis is a body of epidemiological research linking childhood leukaemia risk to chronic exposure above 300–400 nT, a level the SBM-2008 classifies as severe concern.
RF / High-Frequency Radiation
Radiofrequency (RF) radiation is emitted by WiFi routers, smartphones, DECT cordless phones, smart meters, Bluetooth devices, and nearby cell towers. It is the fastest-growing electromagnetic exposure in homes over the past two decades. The SBM-2008 thresholds for RF, measured in microwatts per square metre (µW/m²), are among the most precautionary of any published guideline in the world.
| Concern Level | Power Density (µW/m²) |
|---|---|
| No Concern | < 0.1 |
| Slight Concern | 0.1 – 10 |
| Severe Concern | 10 – 1,000 |
| Extreme Concern | > 1,000 |
A typical WiFi router at one metre produces 10,000–100,000 µW/m², classifying it as extreme concern under the SBM-2008. The FCC public exposure limit is 10,000,000 µW/m², 100 million times higher than the "No Concern" threshold. This difference reflects the SBM-2008's precautionary philosophy versus the government limit's thermal-injury basis.
The most effective RF reduction step in most homes is switching to wired Ethernet and turning off the WiFi router, particularly overnight. See the EMF assessment guide for measurement methods and the RF radiation guide for a full remediation hierarchy.
Dirty Electricity
Dirty electricity refers to high-frequency voltage transients, rapid fluctuations superimposed on the normal 50/60 Hz sine wave in household wiring. Sources include switching power supplies, LED and CFL dimmers, solar inverters, variable-speed motor drives, and some appliances. It is measured in GS units (Graham-Stetzer units) using a Stetzerizer meter.
| Concern Level | GS Units |
|---|---|
| No Concern | < 25 |
| Slight Concern | 25 – 50 |
| Severe Concern | 50 – 200 |
| Extreme Concern | > 200 |
A typical North American home averages 200–500 GS units, well into extreme concern. See the dirty electricity guide for measurement and remediation.
Indoor Air Quality
Volatile Organic Compounds (VOCs)
Total VOC concentration is measured in micrograms per cubic metre (µg/m³). Sources include synthetic paints, adhesives, pressed wood products, carpeting, cleaning products, and off-gassing from new furniture and building materials.
| Concern Level | Total VOCs (µg/m³) |
|---|---|
| No Concern | < 100 |
| Slight Concern | 100 – 300 |
| Severe Concern | 300 – 3,000 |
| Extreme Concern | > 3,000 |
Formaldehyde
Formaldehyde is a Group 1 carcinogen that off-gasses from MDF, particle board, plywood, laminate flooring, and many adhesives. Measured in micrograms per cubic metre.
| Concern Level | Formaldehyde (µg/m³) |
|---|---|
| No Concern | < 20 |
| Slight Concern | 20 – 60 |
| Severe Concern | 60 – 120 |
| Extreme Concern | > 120 |
The WHO guideline for formaldehyde is 100 µg/m³, the SBM-2008 "No Concern" threshold of 20 µg/m³ is five times more stringent. See the VOC and formaldehyde testing guide.
Carbon Dioxide (CO₂)
CO₂ is a reliable proxy for ventilation adequacy, and at elevated concentrations causes measurable cognitive impairment. The SBM-2008 thresholds reflect optimal ventilation performance.
| Concern Level | CO₂ (ppm) |
|---|---|
| No Concern | < 600 |
| Slight Concern | 600 – 1,000 |
| Severe Concern | 1,000 – 2,000 |
| Extreme Concern | > 2,000 |
Radon
Radon is a naturally occurring radioactive gas that seeps from soil and rock. It is the second leading cause of lung cancer after smoking. Measured in Becquerels per cubic metre (Bq/m³) or picocuries per litre (pCi/L).
| Concern Level | Radon (Bq/m³) | Radon (pCi/L) |
|---|---|---|
| No Concern | < 40 | < 1.1 |
| Slight Concern | 40 – 100 | 1.1 – 2.7 |
| Severe Concern | 100 – 400 | 2.7 – 10.8 |
| Extreme Concern | > 400 | > 10.8 |
The EPA action level is 148 Bq/m³ (4 pCi/L), classified as severe concern under the SBM-2008. See the radon testing guide.
Thermal Comfort
The SBM-2008 addresses indoor temperature and humidity as part of the healthy building assessment. Optimal sleeping temperature is 16–18°C (61–64°F). Relative humidity should remain between 40% and 60% to prevent both dry-air irritation and conditions that promote mold growth and dust mite proliferation.
Surface temperatures matter as much as air temperature. Cold exterior wall surfaces cause radiant heat loss even when air temperature is comfortable. A well-insulated wall should have an interior surface temperature within 3–4°C of air temperature. See the insulation guide for retrofit options.
Acoustics
Chronic noise exposure disrupts sleep architecture and elevates cortisol, increasing cardiovascular risk even at levels well below hearing damage thresholds. The SBM-2008 nighttime thresholds are based on sleep research, not hearing protection standards.
| Concern Level | Nighttime Sound Level (dBA) |
|---|---|
| No Concern | < 25 |
| Slight Concern | 25 – 35 |
| Severe Concern | 35 – 45 |
| Extreme Concern | > 45 |
SBM-2008 vs Government Exposure Limits
The most important thing to understand about the SBM-2008 is what it is not: it is not a safety standard in the regulatory sense. Government exposure limits (FCC, ICNIRP, OSHA) set thresholds below which acute harm is prevented. The SBM-2008 sets thresholds below which precautionary best practice is satisfied, a much lower and more protective bar.
A home can fully comply with every government limit while still scoring "Extreme Concern" on multiple SBM-2008 parameters. That is not a contradiction, the standards answer different questions. Government limits ask: at what level does provable acute harm occur? The SBM-2008 asks: what level is consistent with the healthiest possible indoor environment based on the precautionary principle?
The 25 Principles of Building Biology provide the philosophical framework behind these thresholds. The SBM-2008 provides the specific, measurable numbers.
Getting a Building Biology Assessment
A certified building biologist uses the SBM-2008 as their measurement protocol. An assessment typically covers:
- AC electric fields (V/m) and body voltage (mV) at sleeping positions
- AC magnetic fields at sleeping positions and throughout the home
- RF radiation from WiFi, cell towers, DECT, smart meters, and other sources
- Dirty electricity on each circuit
- CO₂, temperature, and humidity
- Visual mold inspection and, where indicated, air or surface sampling
- Material review for VOC and formaldehyde sources
The result is a written report with concern-level ratings for each parameter and a prioritised remediation plan. Find a certified consultant in our building biologist directory, or use the healthy home checklist to assess your home yourself before scheduling a professional visit.