C:\a>go version
go version go1.5.3 windows/386

C:\a>type main.go
package main

import (
        "fmt"
        "syscall"
        "time"
)

func main() {
        zi, found := syscall.Getenv("ZONEINFO")
        fmt.Printf("Found zoneinfo env: %v, location: '%v' .\n", found, zi)

        str := getTimeString("Asia/Hong_Kong", time.Now())
        fmt.Println(str)
}

func getTimeString(strLocation string, ts time.Time) string {
        const MyRFC3339 = "2006-01-02T15:04:05.0000Z07:00"

        var loc *time.Location
        println("--------------")
        loc, err := time.LoadLocation(strLocation)
        if err != nil {
                fmt.Println(err)
                return ""
        }

        return ts.In(loc).Format(MyRFC3339)
}

C:\a>copy %GOROOT%\lib\time\zoneinfo.zip c:\
        1 file(s) copied.

C:\a>set ZONEINFO=C:\zoneinfo.zip

C:\a>go run main.go
Found zoneinfo env: true, location: 'C:\zoneinfo.zip' .
--------------
2016-02-11T14:01:45.7686+08:00

C:\a>del %GOROOT%\lib\time\zoneinfo.zip

C:\a>go run main.go
Found zoneinfo env: true, location: 'C:\zoneinfo.zip' .
--------------
2016-02-11T14:02:02.7219+08:00

C:\a>