There are so many ways to deal with screamers:
1) Surround your base with 1-2 rows of spike traps, look over them and repair from time to time.
2) Make a bigger base and distribute the heat generating items over the range that heat is generated
3) Create multiple farms or separate your farms from the main base
The mechanic of "heat generation" is similar to activity measurement in other games, it simply is an abstration of how you are active in that area. And zombies visiting you in a zombie game should not be a surprise to you. Zombies are not Zombies-for-hire, you can't say "Hey, the next hour doesn't suit me, please come back another time, or wait, I'll visit you in that POI in a few hours". They game never worked that way and will never in vanilla.