# Where should you start measuring?

> Measure all four quantities at the sleeping position first, then fix the largest measured contributor one change at a time. The best interventions are usually free.

- Canonical URL: https://emfbase.com/questions/what-should-i-measure-first
- Collection: Direct answers
- Record id: `questions:what-should-i-measure-first`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/questions/what-should-i-measure-first
- Also known as: reduce EMF at home, EMF survey where to start

## Key values

- **Topic:** measurement

## Question

I want to reduce EMF at home — what do I do first?

## Answer

Measure before buying anything: the most common expensive mistake is shielding a wall while the dominant source is a router in the same room. Survey the sleeping area for all four quantities — RF power density, AC magnetic field, AC electric field and body voltage — grade each against its own band, then fix whichever sits furthest into its band, one change at a time, re-measuring after each. In most homes the largest reductions come from free actions: relocating or scheduling the router, replacing a legacy DECT base, unplugging bedside devices at the socket, and moving a bed away from the service-panel wall.

## Related records

- [Sleeping-area assessment (full four-quantity survey)](https://emfbase.com/protocols/sleeping-area-assessment): The combined survey building-biology practice applies to a bedroom: RF power density, AC magnetic field, AC electric field and body voltage, each graded against its own band.
- [RF room survey](https://emfbase.com/protocols/rf-room-survey): How to measure radiofrequency exposure in a room so the result is reproducible: peak and average, at body positions, with the dominant direction identified.
- [ELF magnetic field survey](https://emfbase.com/protocols/elf-magnetic-survey): A source-finding walkthrough plus a 24-hour log, because power-frequency magnetic fields track electrical load and a spot reading answers almost nothing.

## Sources

- `sbm-2024` Institut für Baubiologie + Nachhaltigkeit (IBN) (2024). *Building Biology Evaluation Guidelines for Sleeping Areas (SBM-2024)*. https://buildingbiology.com/site/downloads/SBM-2024_EVALUATION_GUIDELINES_EN.pdf — ngo, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.