Building a healthier house starts before the walls close.

An air purifier or a filter pitcher can be bought after move-in. Ducts, an outdoor air intake, a drain for water equipment, sound insulation and the structure under a cold plunge cannot be added later without opening finished walls. So healthy home construction starts with the drawings.

California already sets a floor. Two parts of the state building code apply to a new house. The Energy Code (Title 24, Part 6) sets the ventilation rules. CALGreen (Title 24, Part 11) limits what finishes, adhesives, flooring and composite wood may give off. The 2025 Energy Code applies to buildings whose permit applications are made on or after January 1, 2026, and the 2025 CALGreen measures took effect on the same date. Ask your architect which edition your permit is under.

In a whole-home remodel the rules reach less far. CALGreen applies to an addition or alteration that increases the home’s conditioned area, volume or size, and only within that area. The whole-house ventilation rule applies to an addition that increases the home’s conditioned floor area by more than 1,000 square feet. Anything beyond the code is a choice the design team makes and writes into the drawings. Our part is to build it as drawn.

Every new home in California needs a whole-house mechanical ventilation system, and opening windows does not count toward it. The system can exhaust air, supply it, or do both in balance. A balanced system can include a heat recovery or energy recovery ventilator, which passes heat from the outgoing air to the incoming air. Mechanical systems that supply air to habitable spaces need a MERV 13 or better filter, and they have to be designed for that filter’s rated pressure drop at the design airflow.

Kitchens and bathrooms need their own exhaust to the outdoors. A range hood that only recirculates does not meet the requirement. In a home over 1,500 square feet, a hood over a gas range needs a capture efficiency of 70% or an airflow of 180 cubic feet a minute. Over an electric range the figures are 50% or 110 cubic feet a minute. Capture efficiency is the fraction of an emitted test gas that the range hood exhausts directly. An independent rater, called an ECC-Rater, visits the site to verify the ventilation airflow and the hood’s airflow or capture efficiency and sound ratings.

The code leaves open where it all goes. A balanced system needs two duct runs to the outdoors and a unit someone can reach to change filters. The code also requires the outdoor air intake to sit away from known sources of outdoor contaminants, which in practice means away from the driveway, the grill and the dryer vent. The 2025 edition revised the single-family rules: balanced and supply-only systems now have requirements on access to the filters and the recovery unit, and on the intake’s design, location and access. A large hood needs a duct path through the floor or roof above it. All of this is settled at framing.

During construction, CALGreen requires duct openings and air intakes to stay covered from rough-in until the system is started, to keep dust, water and debris out.

Whole-house water treatment is equipment with a footprint. Filter housings, any softener the design team chooses, and their tanks sit where the water main enters the house, before the lines split to the rooms. They need a drain for backwashing, an outlet, a bypass valve so the house keeps water during service, and clear space in front for changing cartridges.

Decide the system before plumbing rough-in. Have the specialist test the supply water first and specify equipment against the results. In a remodel the main often enters at the garage or a side yard, and finding a dry, reachable place there is a layout question for the architect.

CALGreen sets the emission limits a new California home has to meet. VOCs, or volatile organic compounds, are chemicals that evaporate from a product into the air. Adhesives, sealants and caulks must meet the South Coast Air Quality Management District’s Rule 1168 VOC limits, or stricter local rules. Paints and coatings must meet the VOC limits in the Air Resources Board’s suggested control measure for architectural coatings. Carpet, carpet cushion and at least 80% of the floor area that receives resilient flooring must meet the California Department of Public Health’s standard method for testing emissions (Version 1.2, also called Specification 01350). Hardwood plywood, particleboard and medium density fiberboard, inside or outside, must meet the Air Resources Board’s formaldehyde limits for composite wood.

Those limits apply to what is installed, which is not always what was specified. On a house with many trades, the weak point is usually a substitute product. Low-VOC building materials are easiest to secure when the standard is written into the specifications before bidding, so every trade prices to it. A trade that has priced an ordinary product will ask for a change order to switch.

Ask suppliers for the emissions test report or the formaldehyde compliance label in writing before the order is placed, and keep those sheets with the permit file. Cabinets and millwork are mostly composite wood, so the shop drawings should name the core panel and its compliance. The code says nothing about loose furniture, so the designer decides whether a stricter standard applies there.

CALGreen also covers moisture. It does not allow materials with visible water damage to be installed, and wall and floor framing cannot be closed in while it is above 19% moisture content, checked with at least three documented meter readings. Wet insulation is replaced or dried first.

Daylight, the part of wellness architecture people notice first, comes from the architect’s plan and window schedule. The code requires each habitable room to have operable windows with a free opening of at least 4% of its floor area. The builder’s part is to frame the openings, skylights and light wells as drawn, and to keep them square and watertight.

Lighting control has to be wired before drywall. If the designer wants dimming, scenes or warmer light in the evening, the fixture types, circuits, wall box locations and the space for a control panel are fixed at rough electrical. Our article on smart home features covers how to choose the controls.

Most sound control goes in at framing: insulation in the interior walls around bedrooms and bathrooms, and drain lines routed away from bedroom walls. Fan noise is partly in the code: fans that run continuously for whole-house ventilation must be rated at 1.0 sone or less, and a kitchen hood must have at least one setting of 100 cubic feet a minute or more at 3.0 sones or less. Equipment mounted outside habitable spaces is exempt from the sound limits where at least 4 feet of duct separate the fan from the grille. That is one more reason to put the mechanical room away from the bedrooms.

Air handlers, the ventilation unit, water treatment, the water heater and the panels for controls and networking all want the same things: floor space, power, a drain, room to work and a way to get the equipment in and out. In many Los Angeles houses they end up spread across the attic, the garage and a closet. Grouping them in one room makes service easier and keeps the noise in one place.

Size the room from the equipment the engineer and specialists select, plus the clearances their instructions require. Give it a floor drain, lighting, and a door wide enough for the largest unit. Check that the duct routes out of it do not cross a beam.

The Energy Code requires the ventilation controls to be labeled and the owner to receive instructions for operating the system. Ask for every manual, filter size and service interval in one file at handover.

A home sauna and cold plunge are rooms with their own structural, electrical, water and ventilation needs. In planning terms a home wellness room with a steam shower sits closer to a bathroom than to a gym.

A sauna needs a dedicated circuit sized for its heater, an insulated enclosure with a vapor barrier, and an air inlet and outlet placed where the heater manufacturer’s instructions say. The glass and door hardware must be suited to the heat. Settle the heater and the control location before framing, because both set the wiring and the blocking in the walls.

A steam room asks the most of waterproofing. Steam reaches every surface, so the walls and ceiling need a continuous vapor-proof membrane, and the ceiling is usually sloped so condensation runs down a wall instead of dripping. The room also needs a tight door, a floor drain, and a steam generator placed within the distance its instructions allow, somewhere it can be serviced.

A cold plunge is heavy when full, and the structural engineer has to check the floor under it, especially over a garage or on an upper level. Its chiller makes noise and gives off heat, so it goes somewhere ventilated and away from bedrooms, with an access panel, a drain and its own circuit.

For wellness home design as a whole, our wellness construction page covers how these rooms are coordinated with the design team and specialist trades.

Some checks are required. An independent ECC-Rater visits the site to verify the whole-house ventilation airflow and the kitchen hood ratings. A blower door test of the house’s air leakage is required only when the energy compliance model uses a leakage rate below 2 air changes an hour at 50 pascals.

Testing beyond the code is a choice. Some owners hire an independent company to measure indoor air or water after completion. Agree before construction what will be tested, by whom, at what stage and under what conditions, and put it in the contract. Checking duct airflow before the ceilings close finds problems while they are cheap to fix.

A test measures specific things at one time, under the conditions it records. It can show whether a system delivers the airflow it was designed for, or whether a measured level is below a stated limit. It cannot tell you how a house will affect anyone’s health, and a label on a product or a house is not a measurement.

Start by writing down who owns each system: the mechanical engineer, the architect, the interior designer or a specialist. A healthy home builder should be able to tell you, before pricing, where the ducts, the water equipment and the mechanical room will go, and what each choice adds in time.

Our founder, Alik Konovalenko, has been building in Los Angeles since 2016. Energize Builders holds CSLB license #1112649, class B General Building. Our work includes 74 projects led by an interior designer or architect. We build what the design team specifies. We do not diagnose a house or treat anyone. Our new construction page explains how we work with design teams, and our page for interior designers covers how we coordinate with them.

What is healthy home construction?

It is the building work behind the indoor air, water, materials, light and quiet an owner asks for: ventilation and filtration, space for water treatment, low-emission products, daylight, sound control and a room for the equipment. Most of it is decided in the drawings and built before the walls close.

What does California require for ventilation in a new home?

Under the 2025 Energy Code, a new home needs a whole-house mechanical ventilation system, and opening windows does not count toward it. Kitchens and bathrooms need exhaust to the outdoors, systems that supply air to habitable spaces need a MERV 13 or better filter, and an independent rater visits the site to verify the ventilation airflow.

Are low-VOC building materials required in California?

Yes, for new homes. CALGreen limits VOC content in adhesives, sealants, caulks, paints and coatings, requires carpet and at least 80% of the floor area with resilient flooring to meet a state emissions test method, and sets formaldehyde limits for hardwood plywood, particleboard and medium density fiberboard. Stricter products can be specified on top of that.

Can a builder promise non toxic home building?

No, and we do not, because no builder can test a house for everything. What a builder can do is install the products the design team specifies, get the documents in writing, keep the ducts clean during construction, and arrange the tests the owner and design team agree on.

Can these systems be added in a whole-home remodel?

Many can, while walls and ceilings are open. CALGreen applies only within an addition or alteration that increases the home’s area, volume or size, so in a remodel more of the standard is up to the design team.

What should I look for in a healthy home builder?

Ask how they will keep substitute products out, how ducts are protected during construction, who checks airflow before the ceilings close, and how the mechanical room will be serviced. Check any contractor’s license with the Contractors State License Board.