LEED EMF ID Credit Application
The USGBC/LEED recently denied an Innovation in Design (ID) credit application for Magnetic Field (EMF) Reduction. This post includes the official LEED EMF ID Credit Application. The following text is in the traditional formal of an ID credit application and request for a Credit Interpretation Ruling (CIR). Unfortunately the USGBC did not see the benefit of reducing magnetic fields and questioned long-established best practices for minimizing EMF.
If you think the USGBC should include EMF measures in their “green” building rating system, please join us and sign this petition:
LEED EMF ID Credit Application
IDc3: Innovation – Magnetic Field (EMF) Reduction
Reduce occupant exposure to low-frequency magnetic fields through electrical layout design, shielding, and field verification. Implement best practices for low-EMF electrical installation.
Approach and Implementations
Distance from the source:
Magnetic fields drop off quickly from their source. Therefore distancing known point sources from high-use occupancy areas (e.g., beds) is an effective control measure. Main feed wires from the utility to the home, to the main electric panel, and to subpanels, shall not run immediately behind or under sleeping areas. Beds shall not be located within 10 feet of the main electrical panel or subpanel(s). Beds shall not be located within 5 feet of unshielded point sources such as motors, fans, or lighting transformers.
Best practice wiring methods:
In properly wired electrical cable magnetic fields are low because they cancel each other out from the balanced Hot and Neutral. [See Diagram 1.] Electrical panels will be selected with neutral bus bars running the full length of both sides of the panel. Hots and Neutrals in electrical panels, junction boxes, switches and electrical outlets will be kept together as long as possible. [See Diagram 2.] Neutrals from different branch circuits shall not be ganged together in junction boxes [See Diagram 3], and Neutrals and Grounds shall only be bonded at the main electrical panel.
Shielding from sources:
Magnetic field shielding material shall be installed between occupied areas and known point-sources located within 5 feet of high-use occupancy areas. Where impractical to distance point-sources such as motors, fans, or lighting transformers, magnetic field shielding material shall be utilized to reduce occupant exposure levels. Field verification will test shielding efficacy against such sources, and additional shielding shall be installed if necessary to achieve stated goals for maximum allowable exposure levels in sleeping areas. (See next section and Image A.)
All measures outlined above shall be field verified. The two methods in the last sentence of best-practice wiring methods are included in the National Electrical Code (NEC), but these two errors are tremendously common in the field and electrical inspectors are not trained to identify them. A certified Building Biology Environmental Consulting, using a methodology adopted from the International Institute of Building Biology & Ecology, shall perform separate continuity tests from the N-bus and H-bus to each individual Neutral in every electrical panel. This method will identify if Neutrals from different branch circuits are ganged together, and if Neutrals and Grounds are bonded anywhere other than the main electrical panel. If NEC violations are discovered they will be fixed prior to occupancy.
After passing electrical inspections and the home is powered up, internal fixed loads will be powered ON and a Building Biology Environmental Consultant using a gauss meter shall measure magnetic fields using long-established field assessment protocols from the International Institute of Building Biology & Ecology. Sleeping areas shall be < 1.0 milliGauss (mG) or < 100 nanoTesla (nT), or additional mitigation measures shall be implemented until these thresholds are achieved.
Documentation, Verification and Submittals
Distance from the source, best-practice wiring methods, and magnetic field shielding requirements shall be observed first in electrical design drawings AND verified during field inspections. Magnetic field measurements with all power/loads ON shall be reported for every sleeping area.
Field verification shall be performed by a certified Building Biology Environmental Consultant. At least three field verification photos of each outlined approach (distance, wiring, shielding), AND a signed letter from the Building Biologist, shall be submitted to the LEED-H Rater/Provider in order to verify compliance with credit requirements.
Low-frequency magnetic fields (EMF) have been linked to childhood leukemia and breast cancer in numerous peer-reviewed, published studies from around the world. [See Image C.] Conventional electrical layouts and wiring methods in the US lead to unnecessarily high magnetic fields in residential environments – often higher than what is found immediately below high-voltage electrical transmission lines. Additionally, NEC code violations in the form of wiring errors are extremely common in the field. Requirements outlined in this credit will reduce occupant exposures to magnetic fields associated with the building’s electrical system, and thereby reduce risks of cancer.
In Germany, these EMF control measures are commonplace, and Bau-Biologists (Building Biologists) have been implementing these field-tested and well-understood magnetic field mitigation techniques since the 1950’s. It is simple physics, really. The International Institute of Building Biology & Ecology the only established, third-party American organization offering training and certifications specifically in EMF-mitigation. Establishing precedent awarding green building “points” for EMF-mitigation will encourage more people to become trained in EMF-mitigation and also push the construction industry to address this odorless, invisible contaminant many are blanketed in 24/7.
LEED and USGBC are recognized early adopters, known for exceeding code minimum requirements and adopting more precautionary guidelines protecting occupants from known hazards inside buildings. The proposed maximum allowable magnetic field strength for indoor high-use areas, < 1.0 milliGauss, is based on existing scientific literature and the precautionary principle. [See Image D.]
Following Diagrams Courtesy of Karl Riley’s book, “Tracing EMFs in Building Wiring and Grounding”
Diagram 1: Balanced two-wire cable with canceling magnetic fields.
Diagram 2: Electrical panel wired for minimizing magnetic fields. Note N-bus runs full length of H-bus, and Hots and Neutrals are kept together (m-field cancellation) as long as possible.
Diagram 3: Neutrals from different branch circuits ganged together. VERY common electrical code violation that results in significantly elevated magnetic fields.
Image A: Controversy continues when it comes to maximum allowable exposure guidelines for magnetic fields, but many countries and medical organizations are supporting more precautionary guidelines – especially for sleeping areas.
Image B: Low-frequency (60 Hz) magnetic fields drop off quickly, at rates depending on the type of source. Notice that wiring errors drop off the slowest, ½ the field strength, compared to other common point-sources.
Image C: Summary of evidence linking low-frequency magnetic fields to human health problems. Excerpt from Chapter 17 of the “BioInitiative Report,” a summary of peer-reviewed, published health studies about EMF.
Image D: Scientifically supported precautionary exposure levels of low-frequency magnetic fields to product human health. Excerpt from Chapter 17 of the “BioInitiative Report.”