Concept

Status: first sketch, 27 Sep 2026, revised 21 Oct 2026 (estate owns everything, long leases only, full service, shared utilities, guarded gate, attached garage, gardens, park and sports centre, enclosed padel hall, standby generator; ring road, natural park, water tower), revised 3 Nov 2026 (the four corner houses as a new Type C with a private pool, a perimeter trail in an 8 m green belt, green lanes, outdoor fitness stations; 14 houses on 16.9 rai). Every number is an estimate until replaced by a quote (see plan.md, phase 1). Bracketed numbers such as [5] refer to sources.md.

The idea

A small gated mooban (housing estate) near Chiang Mai that owns every one of its houses and lets them only on long-term leases. Every house is built to one high specification: Passive House level airtightness, insulated envelope, high-performance windows and doors, filtered mechanical ventilation (ERV), efficient cooling, rooftop solar, and an electrical and plumbing installation to B4L's own construction standards. The tenant never deals with a repair: the estate's own team maintains the AC, the electrics, the plumbing and everything else, and the rent includes electricity and water up to an allowance (operating-model.md).

Because one company owns all of it, the estate runs its utilities like one building (utilities.md): one water plant whose pump station fills a water tower, and a looped main from the tower to every house instead of a tank and pump at each house, and one private grid into which every roof's solar feeds, shared by all houses and backed by one central battery and a standby generator, behind a single PEA connection. The estate is gated: one staffed main gate, where residents come in by number plate or card and visitors and deliveries only after the guard has called the house on the intercom and the tenant has said yes (security-and-access.md). The spec and the service together are the product: clean air, quiet, cool, no bills, no repairs, power and water that stay on, and nobody at the door the tenant has not let in.

Every house has its own 9 m garden and stands 7 m from its neighbours. The house at each end of the two outer rows is a larger corner house, Type C (5 bed, about 300 m², a three-car garage and a private pool in its corner garden), for the families who would otherwise rent a pool villa. The houses sit round a natural park on one curved ring road with a roundabout at each end; the club at the east edge has an indoor hall with two badminton courts, a gym, an enclosed hall with two padel courts, a pool and a multi-use court, and a water tower stands beside it. An 8 m planted belt inside the wall carries a 2.5 m trail for running and walking all round the estate, with outdoor fitness stations along it and in the park, and green lanes lead between the houses to the trail and the park. There is no pond or other open water: stormwater goes to a closed tank and to a meadow hollow that is dry again within a day, because standing water breeds mosquitoes, including the Aedes mosquitoes that carry dengue[62][63] (site-plan.md).

Why Chiang Mai needs this kind of house

• Smoke season. Air quality during smoke season (February to April) is something residents need to plan for, and PM2.5 often reaches unhealthy or hazardous levels.[17] Across northern Thailand the regional annual mean PM2.5 for 2020 to 2024 was 40.42 µg/m³, far above the WHO guideline of 5 µg/m³.[18] A normal Thai house leaks, so indoor air follows outdoor air. An airtight house with a filtered ERV at slight overpressure is the fix; one Chiang Mai agency reports that a simple HEPA positive-pressure unit in the living area plus bedroom purifiers kept indoor PM2.5 around 10 or lower on very polluted days.[17]
• Heat. April afternoons typically reach about 37 °C (98.8 °F), and the count of days above 30 °C (86 °F) has risen from about 190 to 315 a year across the station record.[27] Cooling is the biggest electricity load in a Thai home.[12]
• Flooding. In October 2024 the Ping River swelled and flash floods swamped Chiang Mai, killing at least three people.[19] Site choice, fill level and plinth height are part of the specification, not an afterthought. B4L's own Ping River monitor (water.buildfor.life) gives the station history for site screening.
• Earthquakes. Chiang Mai is in Zone 3 of the 2021 seismic ministerial regulation, the highest-impact zone.[24] We design every house to it whether or not the rule strictly applies to a two-storey house.
• No code pushes quality up. The Building Energy Code applies only to buildings of 2,000 m² and more,[23] so a normal house has no energy or airtightness requirement at all. That is the gap.
• Renting a house means running it. Thai leases often leave routine AC cleaning and small repairs to the tenant,[38] and estate houses each have their own tank and pump; users report that on one estate of more than 150 houses over half the owners pump straight from the mains into their own tanks when pressure is low.[44]

Who rents it

Families on relocation packages and long-stay professionals who today rent a normal estate house, run air purifiers in every room for three months a year and chase their own repairs. Chiang Mai's international schools cluster in the Hang Dong and Saraphi corridor south of the city, and families look for gated houses within 10 to 20 minutes of the school gate;[26] fees at the Hang Dong schools range from about 224,000 to 813,000 THB a year,[26] which is the budget class that can pay premium rent. Secondary: retirees and long-stay families who cannot buy land and want a registered long lease (up to 30 years[31]) with someone else looking after the house, and remote workers with health reasons to care about air.

Where

First choice: the Hang Dong / Nong Khwai / Saraphi corridor (schools, Kad Farang, airport, ring road). Prime Hang Dong land runs about 4 to 8 M THB per rai, outer Hang Dong 1 to 3 M THB per rai.[3] Mae Rim is the second option for families at the north-side school.[26] Screening criteria: outside recorded flood extents, road frontage to a public soi, PEA 22 kV supply nearby, groundwater that can be licensed and treated (or a PWA main), no field burning upwind in the valley floor, 15 to 20 minutes to a school gate.

What makes it different from existing estates

The monitoring uses B4L's own hardware where it fits: the SEN66-based AQI sensor (PM, CO₂, VOC, NOx, temperature, humidity) and local, cloud-free Daikin control via ESP32-Faikin, all on a local Home Assistant per house.

The honest problem

A premium house that the landlord also runs for the tenant costs far more than a normal one and must rent for far more than the Chiang Mai market pays for normal houses. costs-and-rent.md puts numbers on it; the short version: about 11.5 to 19.9 M THB all-in per 3-bed house and about 19,400 to 38,500 THB a month in running costs, needing about 80,000 to 144,000 THB a month all-inclusive to earn a 5 % net yield, against 20,000 to 38,000 THB for normal new 3-bed estate houses.[5] The corner Type C with its own pool needs about 194,000. Premium branded estates already reach 70,000 THB for a 184 m² 3-bed,[5] so the rent exists at the top of the market, but it has to be proven before land is bought. Hence a two-house pilot first (plan.md).