The 25 Principles of Building Biology

Your body is your first skin. Your clothing is your second. Your home is your third, and like skin, it breathes, regulates temperature, filters what gets in, and either protects you or exposes you. Building biology starts from this premise: the building envelope is not separate from your health. It is part of it.

In the 1970s, Professor Dr. Anton Schneider at the Institut für Baubiologie + Nachhaltigkeit (IBN) in Germany codified this idea into 25 principles for creating buildings that support human health. These became the foundation of the building biology (Bau-Biologie) discipline. Each principle points to something measurable, testable, or actionable, covering site selection, electromagnetic environments, indoor air, moisture, thermal comfort, acoustics, ergonomic design, and environmental responsibility. Together, they form the basis for the SBM-2008 testing standard and the assessment methods used by certified building biologists worldwide.

Where to start: You do not need to address all 25 principles at once. For most homeowners, the highest-impact areas are EMF reduction in the sleeping environment (Principles 7–8), indoor air quality (Principles 10–13), and non-toxic material selection (Principles 12, 22). If you read nothing else, read those sections first and work outward from there.

Principles 1–4: Site and Community Design

Building biology starts before the first wall goes up. The site itself, its geology, its exposure to pollution, its relationship to the surrounding community, shapes health outcomes for every occupant.

Principle 1: Verify the building site is free of health hazards

The ground beneath a building matters. Geological instability, soil contamination from prior industrial use, naturally occurring radon, and high water tables all pose long-term health risks. Before buying land or building, check environmental site assessments (Phase I ESA), local radon maps, and flood zone designations.

What you can do: Request environmental records for your property. Test for radon, it's inexpensive ($25 for a long-term alpha track test) and radon is the second leading cause of lung cancer after smoking. If you're purchasing land, ask for soil contamination reports.

Principle 2: Protect occupants from air, soil, water, noise, and electro-pollution

The building envelope should function as a filter between the outdoor environment and the indoor living space. Proximity to highways, airports, agricultural pesticide application, industrial emissions, cell towers, and high-voltage power lines all affect what enters the home.

What you can do: Before buying or renting, assess nearby pollution sources. Check your distance from major roads (fine particulate matter drops significantly beyond 150 metres). Note nearby cell towers and power lines. For existing homes, air filtration, acoustic glazing, and EMF shielding are available, but distance from the source is always more effective.

Principle 3: Place homes in well-planned communities with ample fresh air, sunshine, and access to nature

Access to daylight, green space, and clean air directly affects circadian rhythm and respiratory health. Building biology favours low-density, well-ventilated communities with mature trees and minimal traffic.

What you can do: Evaluate sun exposure on your property. South-facing rooms (in the Northern Hemisphere) receive the most daylight. Mature trees provide shade in summer while allowing winter sun. If you're surrounded by concrete and asphalt, even a small garden or indoor plants improve air quality.

Principle 4: Plan considering community, family, and individual needs

A healthy home serves the specific people living in it. A household with young children has different needs than one with an elderly or chemically sensitive occupant. Room layout, material choices, and system design should reflect how the space will actually be used, not just how it looks.

What you can do: Identify the most vulnerable person in your household (typically children, the elderly, or anyone with chronic illness) and design the sleeping environment around their needs first. The bedroom is the single highest-priority space in building biology.

Principles 5–9: Electromagnetic Environment

These five principles address the electromagnetic conditions inside a building, from natural light to artificial EMF. The SBM-2008 standard provides specific measurement thresholds for the categories covered here, particularly AC electric fields, AC magnetic fields, and radiofrequency radiation.

Principle 5: Provide abundant natural light and nature-matching colours

Artificial lighting is a poor substitute for daylight. The human circadian system responds to the full spectrum and intensity of natural light, something no indoor fixture fully replicates. Building biology calls for maximizing natural light penetration and using colours and materials that reflect the natural environment rather than harsh synthetic tones.

What you can do: Prioritise rooms where you spend waking hours for the best natural light. Avoid blocking windows with heavy furnishings. For artificial lighting, choose full-spectrum bulbs with low flicker. Dim or eliminate blue-enriched light in the evening to support melatonin production.

Principle 6: Minimise building material interference with cosmic and terrestrial radiation

The natural electromagnetic environment, the Earth's static magnetic field, the Schumann resonance, the full light spectrum, has been present throughout human evolution. Certain building materials (particularly steel-reinforced concrete, metal cladding, and metallized glass) attenuate or distort these fields. The principle calls for material choices that allow the natural radiation environment to pass through the building envelope where practical.

What you can do: Where possible, favour natural building materials, solid wood, clay, natural stone, lime plaster, over steel-frame and metal-clad construction, particularly in sleeping areas. If you have a metal bed frame, check for geomagnetic distortion with a compass (see SBM-2008, Section E).

Principle 7: Minimise harmful EMF from building electrical systems

Standard residential wiring produces AC electric fields from voltage and AC magnetic fields from current flow. These fields are strongest near the wiring and diminish with distance. In most homes, the bedroom is overexposed because unshielded wiring runs through walls directly behind the bed.

The SBM-2008 sets "No Concern" thresholds at less than 1 V/m for electric field strength (or less than 10 mV body voltage) and less than 20 nT (0.2 mG) for magnetic flux density, levels that are thousands of times below government limits.

What you can do: Install a demand switch (automatic circuit cut-off) on the bedroom circuit, this eliminates voltage in the wiring when no current is being drawn. Unplug chargers and devices near the bed. For new construction, specify shielded wiring (NYM-J type or equivalent). Measure your body voltage at the sleeping position with a multimeter and grounding rod. For a full assessment, consult a certified building biologist.

Principle 8: Shield and avoid radiofrequency radiation

RF radiation from WiFi, cell towers, cordless phones (DECT), smart meters, and Bluetooth devices is the fastest-growing electromagnetic exposure in homes. The SBM-2008 "No Concern" threshold is less than 0.1 µW/m², a level that is 100 million times below the FCC limit. A typical WiFi router exceeds the "Extreme Concern" threshold at one metre.

What you can do: Switch to wired Ethernet for internet, this is the single most impactful change in most homes. Turn off WiFi at night or use a timed switch. Replace DECT cordless phones with corded phones. Keep cell phones in airplane mode on the nightstand. For external sources like cell towers, professional RF assessment should precede any shielding, because incorrect shielding can trap RF energy inside the home.

Principle 9: Prohibit building materials with elevated radioactivity

Some building materials, certain granite, fly ash concrete, phosphogypsum, and slag-based products, contain naturally occurring radioactive elements that elevate indoor gamma radiation and contribute to radon off-gassing. Building biology calls for screening materials before installation.

What you can do: If you're choosing countertop stone, ask the supplier about radioactivity testing. For existing homes, a radon test is the most practical first step, elevated radon can indicate radioactive material in the foundation or soil beneath. The SBM-2008 flags indoor gamma radiation above 50 nSv/h as a slight concern.

Principles 10–14: Indoor Air Quality

We breathe approximately 15,000 litres of air per day. Most of it is indoor air. These principles address the chemical, biological, and physical quality of that air.

Principle 10: Ensure low moisture content and rapid drying in new construction

New buildings contain enormous amounts of construction moisture, concrete, plaster, paint, and adhesives all release water vapour as they cure. Moving in before the structure has dried sufficiently traps this moisture inside, creating conditions for mold growth, chemical off-gassing, and structural damage.

What you can do: If building new or after major renovation, allow adequate drying time before moving in. Ventilate aggressively during and after construction. Monitor indoor humidity, it should stabilise between 40–60% before occupancy. Avoid sealing surfaces (painting, wallpapering) before the substrate has fully dried.

Principle 11: Provide ample ventilation

Adequate air exchange is the single most effective way to maintain indoor air quality. CO₂ levels are the simplest proxy, a closed bedroom with two occupants can exceed 2,000 ppm by morning, causing grogginess and impaired cognition. The SBM-2008 targets below 600 ppm.

What you can do: Open windows for cross-ventilation daily, even briefly in winter. A CO₂ monitor ($50–100) gives real-time feedback. If the bedroom consistently exceeds 1,000 ppm overnight, consider a trickle vent or mechanical ventilation with heat recovery (MVHR). See the indoor air quality testing guide for measurement methods.

Principle 12: Use non-toxic building materials

Many conventional building materials emit volatile organic compounds (VOCs), formaldehyde, phthalates, flame retardants, and other chemicals that accumulate in indoor air. Pressed wood products (MDF, particle board), vinyl flooring, synthetic carpeting, and spray foam insulation are among the worst offenders.

The SBM-2008 flags total VOCs above 200 µg/m³ as a slight concern and formaldehyde above 20 µg/m³, well below the WHO guideline of 100 µg/m³.

What you can do: Choose solid wood, natural linoleum, stone, tile, or concrete for flooring. Use clay or lime plaster instead of synthetic paints where feasible. When painting, choose zero-VOC or natural paints and allow full curing time. For a detailed material selection guide, see non-toxic building materials. Test existing spaces with a VOC and formaldehyde test if you suspect chemical off-gassing.

Principle 13: Use appropriate moisture exclusion to prevent fungi, bacteria, and dust mites

Mold, bacteria, and dust mites thrive in damp conditions. Persistent relative humidity above 70% at any surface, walls, window frames, under-ventilated corners, is enough. Thermal bridges (poorly insulated spots where warm interior air meets cold surfaces) are the most common sites for condensation and mold growth.

What you can do: Address thermal bridges, these are typically at window frames, exterior wall junctions, and uninsulated lintels. Ensure bathrooms and kitchens have adequate exhaust ventilation. Don't push furniture flush against cold exterior walls. Monitor humidity in problem areas with a hygrometer. If mold is visible or suspected, see the mold testing guide before disturbing it.

Principle 14: Ensure best possible water quality

Building biology extends to the water supply. Pipe materials, water treatment processes, stagnation in pipes, and source contamination all affect what comes out of the tap. Lead solder in older plumbing, copper pipe corrosion, and disinfection byproducts are common concerns.

What you can do: Test your tap water, many labs offer panels for lead, copper, nitrates, chlorine byproducts, and microbial contamination. Run the tap for 30 seconds before drinking if water has been sitting in pipes overnight. Consider a point-of-use carbon block filter for drinking water. If your home has pre-1986 plumbing, test specifically for lead.

Principle 15: Moisture Self-Regulation

Principle 15: Allow natural self-regulation of indoor humidity using hygroscopic materials

Hygroscopic materials, clay, lime plaster, solid wood, natural fibre insulation, wool, cotton, absorb moisture when humidity rises and release it when humidity drops. They act as passive buffers, smoothing out the spikes and troughs that mechanical systems handle poorly. A room finished in clay plaster maintains more stable humidity than one finished in vinyl paint on gypsum board.

What you can do: Favour breathable wall finishes: clay plaster, lime plaster, silicate paint. Choose solid wood or natural fibre furniture and textiles. Avoid impermeable layers (vinyl wallpaper, oil-based paints on interior walls, plastic vapour barriers on the warm side of walls in mild climates) that prevent moisture exchange. In a well-designed building biology home, the walls themselves help regulate the indoor environment.

Principles 16–18: Thermal Comfort

Thermal comfort is more than air temperature. Surface temperatures, radiant heat, and the balance between insulation and thermal mass all affect how a space feels and how your body regulates temperature.

Principle 16: Design climatically appropriate thermal insulation and storage balance

Insulation keeps heat in (or out). Thermal mass (heavy materials like concrete, brick, stone, or earth) stores heat and releases it slowly, buffering temperature swings. The right balance depends on your climate. A cold-climate home needs high insulation with enough thermal mass to store solar gains. A hot-arid climate needs heavy thermal mass with nighttime ventilation. Getting this wrong leads to overheating, energy waste, or both.

What you can do: If your home overheats in summer despite air conditioning, you may lack thermal mass. If it cools down rapidly when heating stops, you may lack both insulation and mass. For retrofits, adding insulation to the exterior preserves interior thermal mass, interior insulation can actually make thermal mass less effective.

Principle 17: Plan for appropriate surface and air temperatures

Cold wall surfaces cause discomfort even when air temperature is adequate, the body loses heat by radiation to any surface cooler than skin temperature. A well-insulated wall with a surface temperature above 17°C eliminates this radiant heat loss. Poor insulation forces higher air temperatures to compensate, wasting energy and drying out the air.

What you can do: If you feel cold near exterior walls despite adequate air temperature, the wall surface may be too cold. An infrared thermometer ($20–40) lets you check. The fix is usually exterior insulation or addressing thermal bridges at junctions and window reveals.

Principle 18: Use appropriate thermal radiation strategies

Radiant heating, from a wood stove, a masonry heater, heated floor, or radiant wall panels, warms surfaces and occupants directly rather than heating the air. This produces more even warmth at lower air temperatures, with less air movement and less dust circulation. Building biology favours radiant heat sources over forced-air systems.

What you can do: If you're choosing or upgrading a heating system, consider radiant floor heating or wall-mounted radiant panels. If you have forced-air heating, regular duct cleaning and high-quality filtration help reduce the dust and allergen circulation that convective systems promote.

Principle 19: Acoustics

Principle 19: Provide adequate acoustical protection

Chronic noise exposure, even at levels well below those that damage hearing, disrupts sleep, elevates cortisol, and increases cardiovascular risk. The SBM-2008 flags nighttime sound levels above 25 dBA as a slight concern. For reference, a quiet rural area at night measures 20–25 dBA; a refrigerator hum is about 35–40 dBA.

What you can do: Identify the primary noise sources: traffic, neighbours, mechanical systems, appliances. Acoustic glazing (double or triple-pane windows with different glass thicknesses) is the most effective retrofit for external noise. For internal noise, soft furnishings, carpets, and acoustic panels reduce reverberation. Move the bedroom to the quietest side of the house if possible.

Principles 20–21: Human-Based Design

Building biology also accounts for how spaces affect the body physically and psychologically.

Principle 20: Utilise physiological and ergonomic knowledge in design

Room dimensions, ceiling heights, stair geometry, workstation layout, and furniture proportions all affect physical health. Poorly designed stairs cause falls. Incorrect desk heights cause musculoskeletal problems. Inadequate ceiling height creates compression that raises stress levels.

What you can do: Evaluate your most-used spaces for ergonomic fit. Is your desk at the right height? Does your kitchen require excessive reaching or bending? Are stair risers and treads uniform? Small adjustments, monitor height, counter height, chair support, can have outsized effects on daily comfort and long-term health.

Principle 21: Consider proportion, harmonic measure, order, and shape

This principle draws on the long architectural tradition of proportional systems, from the golden ratio to classical module systems. Spaces with coherent proportions, natural materials, and visual order feel different from chaotic, disproportionate ones. Environmental psychology research backs this up: visual complexity within order reduces stress, while disorder increases it.

What you can do: You don't need to redesign your house. Reduce visual clutter, particularly in the bedroom. Choose furnishings with consistent proportions and natural textures. Let the space breathe, overcrowded rooms with mismatched elements create low-level sensory noise that most people stop noticing but never stop reacting to.

Principles 22–25: Environmental Protection

The final four principles extend beyond the occupant to the planet. A healthy building cannot depend on environmental destruction to build or operate.

Principle 22: Ensure materials promote health from extraction through end-of-life

A material is not "non-toxic" if its manufacture poisons workers or its disposal contaminates groundwater. Building biology evaluates materials across their full life cycle, mining, manufacturing, transportation, installation, use, and eventual demolition or recycling. PVC, for example, may be stable once installed, but its manufacture produces dioxins and its incineration releases hydrochloric acid.

What you can do: Favour materials with transparent supply chains: FSC-certified wood, locally sourced stone, recycled metals, natural fibre insulation (cellulose, wood fibre, sheep's wool). Avoid materials with complex chemical formulations that make recycling impossible.

Principle 23: Avoid materials that deplete irreplaceable natural resources

Some building materials rely on finite, non-renewable resources, sand for concrete (river sand is increasingly scarce), old-growth timber, rare minerals, and petroleum-derived products. Building biology calls for renewable, abundant, and locally available alternatives where they exist.

What you can do: Choose renewable materials: bamboo, cork, straw bale, rammed earth, hempcrete, reclaimed timber. For insulation, cellulose (made from recycled paper) and wood fibre perform well and are fully renewable. When concrete is necessary, specify supplementary cementitious materials (fly ash, slag) to reduce the cement content.

Principle 24: Minimise energy consumption throughout building life

Operational energy, heating, cooling, lighting, and appliances, accounts for the majority of a building's lifetime energy use. Passive design strategies (orientation, insulation, thermal mass, natural ventilation, daylighting) reduce this demand before any mechanical system gets involved.

What you can do: Start with the building envelope: insulation, air sealing, and window performance. These yield the highest return. Then address heating and cooling efficiency. LED lighting and efficient appliances are the lowest-cost improvements. A blower door test ($150–400) reveals where your building leaks air, and where insulation investment will pay off most.

Principle 25: Consider embodied energy and environmental life-cycle costs

Embodied energy is the total energy required to produce a material, from raw extraction through manufacturing and transportation. Aluminium, for example, requires roughly 170 MJ/kg to produce; timber requires about 2 MJ/kg. As buildings become more energy-efficient in operation, embodied energy makes up a larger share of the total life-cycle impact.

What you can do: When choosing between materials with similar performance, favour the one with lower embodied energy. Locally sourced materials reduce transportation energy. Renovation and reuse of existing buildings almost always beat demolition and new construction on embodied energy. If building new, a life-cycle assessment (LCA) can quantify the environmental cost of different material choices.

Putting the Principles Into Practice

Start with the bedroom, the space where you spend a third of your life and where sleep quality matters most. The highest-impact changes for most homes fall into three areas:

1. EMF reduction in the sleeping area, demand switches, wired internet, phones on airplane mode (Principles 7–8)
2. Indoor air quality, ventilation, material selection, moisture control (Principles 11–13)
3. Non-toxic materials, eliminating formaldehyde, VOCs, and synthetic chemicals at the source (Principle 12)

The healthy home checklist provides a room-by-room walkthrough based on these principles. If you want measurements rather than estimates, start with the SBM-2008 testing thresholds, they give you specific numbers to measure against.

Your home is your third skin. These 25 principles are a way of evaluating whether it's doing its job, and where it might need attention. Pick the area that matters most to your household, measure it, and improve it. Then move to the next one.

For professional guidance, a certified building biologist can assess your home against these principles using calibrated instruments and provide a prioritised remediation plan tailored to your household.