Final with flowchart

#include <DHT.h>

#define DHTPIN 8
#define DHTTYPE DHT11   // DHT 11
DHT dht(DHTPIN, DHTTYPE);

#include <NewPing.h>

#define TRIGGER_PIN_IN 9
#define ECHO_PIN_IN 10
#define MAX_DISTANCE_IN 200

#define TRIGGER_PIN_OUT 11
#define ECHO_PIN_OUT 12
#define MAX_DISTANCE_OUT 200

NewPing sonar_in(TRIGGER_PIN_IN, ECHO_PIN_IN, MAX_DISTANCE_IN);
NewPing sonar_out(TRIGGER_PIN_OUT, ECHO_PIN_OUT, MAX_DISTANCE_OUT);

#include <LiquidCrystal.h>

LiquidCrystal lcd(2, 3, 4, 5, 6, 7);

int count = 0;
int piezoelectric = 1;

void IN()
{
  if ( piezoelectric = 1) {
    count++;
    lcd.setCursor(0, 0);
    lcd.print("N:");
    lcd.setCursor(4, 0);
    lcd.print(count);
    lcd.setCursor(7, 0);
    lcd.print("Persons");
    }
    if ( count < 0 ) {
      count = 0;
      lcd.clear();
    }
    delay(1000);
}

void OUT()
{
    if ( piezoelectric = 1) {
      count--;
      lcd.setCursor(0, 0);
      lcd.print("N:");
      lcd.setCursor(4, 0);
      lcd.print(count);
      lcd.setCursor(7, 0);
      lcd.print("Persons");
    }
    if ( count < 0 ) {
      count = 0;
      lcd.clear();
    }
    delay(1000);
}

void setup()
{
    if ( piezoelectric = 1) {
      Serial.print(9600);
      lcd.begin(16, 2);
      lcd.setCursor(0, 0);
      lcd.print("N:");
      lcd.setCursor(4, 0);
      lcd.print(count);
      lcd.setCursor(7, 0);
      lcd.print("Persons");
    }
    if ( count < 0 ) {
      count = 0;
      lcd.clear();
    }
    delay(250);
}
// Existed loops
void loop () {
 inout ();
 temphumid();
}
void inout () {
  unsigned int uS1 = sonar_in.ping();
  int distance1 = uS1 / US_ROUNDTRIP_CM;
  if(distance1 != 0 && distance1 <=40){
    IN();
  }
  unsigned int uS2 = sonar_out.ping();
  int distance2 = uS2 / US_ROUNDTRIP_CM;
  if(distance2 != 0 && distance2 <=40){
    OUT();
  }
}

 // Start of reading temperature and humidity
 
void temphumid ()
{
  int h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  int t = dht.readTemperature();
  lcd.setCursor(0, 1);
  lcd.print("H:");
  lcd.setCursor(3, 1);
  lcd.print(h);
  lcd.setCursor(5, 1);
  lcd.print("%");
  lcd.setCursor(8, 1);
  lcd.print("T:");
  lcd.setCursor(11, 1);
  lcd.print(t);
  lcd.setCursor(14, 1);
  lcd.print("*C");
  if ( 18 <= t <= 26 && 30 <= h <= 70 ) {
    Serial.println("Thermal comfort is achieved");
  }
    else {
      Serial.println("Open windows");
    }
  delay (500);
}