diff --git a/central_backend/src/energy/mod.rs b/central_backend/src/energy/mod.rs
index c080861..2922113 100644
--- a/central_backend/src/energy/mod.rs
+++ b/central_backend/src/energy/mod.rs
@@ -1,3 +1,4 @@
 pub mod consumption;
 pub mod energy_actor;
 pub mod engine;
+pub mod relay_state_history;
diff --git a/central_backend/src/energy/relay_state_history.rs b/central_backend/src/energy/relay_state_history.rs
new file mode 100644
index 0000000..117e094
--- /dev/null
+++ b/central_backend/src/energy/relay_state_history.rs
@@ -0,0 +1,44 @@
+use crate::devices::device::DeviceRelayID;
+
+/// # RelayStateHistory
+///
+/// This structures handles the manipulation of relay state history files
+///
+/// These file are binary file optimizing used space.
+pub struct RelayStateHistory {
+    id: DeviceRelayID,
+    day: usize,
+    buff: Vec<u8>,
+}
+
+impl RelayStateHistory {
+    /// Open relay state history file, if it exist, or create an empty one
+    pub fn open(id: DeviceRelayID, day: usize) -> anyhow::Result<Self> {
+        todo!()
+    }
+
+    /// Create a new in memory dev relay state history
+    fn new_memory(id: DeviceRelayID, day: usize) -> Self {
+        todo!()
+    }
+
+    /// Resolve time offset of a given time in buffer
+    fn resolve_offset(&self, time: i64) -> anyhow::Result<(usize, u8)> {
+        todo!()
+    }
+
+    /// Set new state of relay
+    fn set_state(&mut self, time: i64, on: bool) -> anyhow::Result<()> {
+        todo!()
+    }
+
+    /// Get the state of relay at a given time
+    fn get_state(&self, time: i64) -> anyhow::Result<bool> {
+        todo!()
+    }
+
+    /// Persist device relay state history
+    pub fn save(&self) -> anyhow::Result<()> {
+        todo!()
+    }
+}