Arduino + Ethernet + Buzzer

Hi guys, i have project to built an electricity home monitoring, i use arduino r3 + ethernet +buzzer. My question is how to built automatic on/off buzzer when the power (input from php web that save on mysql) is limit?

#include <SPI.h>
#include <Ethernet.h>
#include “EmonLib.h”
#include <LiquidCrystal.h>
//Ethernet shield attached to pins 10, 11, 12, 13
LiquidCrystal lcd(8, 9, 5, 4, 3, 2);
byte mac = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
IPAddress ip(192,168,1,20);

IPAddress myDns(192,168,1,1);

EthernetClient client;

//char server = “192.168.1.1”;
byte server = {192,168,1,1};
unsigned long lastConnectionTime = 0;
boolean lastConnected = false;
const unsigned long postingInterval = 6*1000;
EnergyMonitor emon1;

void setup()
{
Serial.begin(9600);
Ethernet.begin(mac, ip, myDns);
Serial.print(“My IP address: “);
Serial.println(Ethernet.localIP());
lcd.begin(16, 2);
emon1.current(1, 20);
}
void loop()
{
httpRequest();
}
void httpRequest() {
// if there’s a successful connection:
if (client.connect(server, 80)) {
Serial.println(“connecting…”);
double Irms = emon1.calcIrms(1480);
float Daya = Irms*220;
// send the HTTP PUT request:
client.print(“GET /emon/insert.php?tarus=”);
client.print(Irms);
client.print(”&tdaya=”);
client.print(Daya);
client.print(" HTTP /1.1");
client.println(“Host: 192.168.1.1”);
client.println(“User-Agent: arduino-ethernet”);
client.println(“Connection: close”);
client.println();

//Menampilkan pada keluaran LCD
lcd.print(“Arus = “);
lcd.print(emon1.Irms);
lcd.print(” A”);
lcd.setCursor(0,1);
lcd.print(“Daya = “);
lcd.print(emon1.Irms*220);
lcd.print(” W”);
lcd.display();
delay(1000);
lcd.clear();

//serial display
Serial.print("Arus = ");
Serial.println(Irms);
Serial.print("Daya = ");
Serial.println(Irms*220);

// note the time that the connection was made:
lastConnectionTime = millis();

}
else {
// if you couldn’t make a connection:
lcd.print(“connection failed”);
lcd.display();
delay(1000);
lcd.clear();
Serial.println(“connection failed”);
Serial.println(“disconnecting.”);
client.stop();
}
}