Real estate
Buying, selling, and investing across San Marino, Arcadia, Pasadena, Temple City, San Gabriel, and Alhambra.
- Negotiation backed by MBA-grade analysis
- Bilingual service (English · Mandarin)
- Neighborhood-level guidance
JoyfulHouse Real Estate · San Gabriel Valley
Find the right house. Then make it brilliant.
A San Gabriel Valley brokerage with an in-house engineering practice — we help you buy well, sell smart, and make the home itself work beautifully.
JoyfulHouse combines San Gabriel Valley brokerage services with in-house AI smart-home and solar engineering. Kofen guides the real estate decision first; the engineering practice is there to make the home work beautifully afterward.
- California licensed
- CalRE# 01951860
- transactions closed
- 88+
- average across 50 client reviews
- 4.9★
- open-source projects maintained
- 17
What we do
AI-integrated smart home
Design and installation of AI-integrated automation — language and vision models run on hardware in your home, so voice, cameras, and daily routines stay private. Local-first, no subscriptions.
Explore AI smart home
Your agent
Kofen Chang
MBA-trained and bilingual in English and Mandarin, Kofen is a REALTOR® who came up through Coldwell Banker Global Luxury in Pasadena and San Marino. She co-founded JoyfulHouse to pair brokerage with engineering.
REALTOR® · CalRE# 01951860 · MBA · WSGVAR member
The engineering practice
We build the tools we install.
The AI smart-home and energy work runs on software we write and maintain in the open — 17 projects used by real homes, including ours.
EG4 Web MonitorLocal Modbus + cloud monitoring and control for EG4 / Luxpower inverters, GridBOSS, and batteries.BrilliantLocal MQTT bridge turning Brilliant in-wall panels into Home Assistant entities — no cloud.QuietCool FansESPHome firmware controlling QuietCool attic and whole-house fans over their native 433 MHz link.
All 17 projects →Service area
San MarinoArcadiaPasadenaTemple CitySan GabrielAlhambra
Let's talk about your house.
Tell Kofen what you're planning, whether you're buying, selling, or thinking ahead.