diff --git a/caimira/apps/calculator/static/js/co2_form.js b/caimira/apps/calculator/static/js/co2_form.js
index eb019c5b..afcf7638 100644
--- a/caimira/apps/calculator/static/js/co2_form.js
+++ b/caimira/apps/calculator/static/js/co2_form.js
@@ -154,8 +154,8 @@ function validateFormInputs(obj) {
   const $referenceNode = $("#DIVCO2_data_dialog");
   for (let i = 0; i < CO2_data_form.length; i++) {
     const $requiredElement = $(`[name=${CO2_data_form[i]}]`).first();
-    if ($requiredElement.attr('name') !== "fitting_ventilation_states" && 
-        $requiredElement.attr('name') !== "room_capacity" && 
+    if ($requiredElement.attr('name') !== "fitting_ventilation_states" &&
+        $requiredElement.attr('name') !== "room_capacity" &&
         $requiredElement.val() === "") {
       insertErrorFor(
         $referenceNode,
@@ -245,7 +245,6 @@ function validateCO2Form() {
     const roomCapacityVal = roomCapacity.val();
     if (roomCapacityVal !== "") {
       const roomCapacityNumber = Number(roomCapacityVal);
-      const totalPeopleNumber = Number($("#total_people").val());
       if (!Number.isInteger(roomCapacityNumber) || roomCapacityNumber <= 0) {
         insertErrorFor(
           $referenceNode,
@@ -255,11 +254,7 @@ function validateCO2Form() {
       }
     }
     else {
-      insertErrorFor(
-        $referenceNode,
-        `'${roomCapacity.attr('name')}' must be defined.</br>`
-      );
-      submit = false;
+      $fittingToSubmit.find("#warning_room_capacity_null").show();
     }
   }
 
@@ -286,6 +281,10 @@ function displayFittingData(json_response) {
   // Not needed for the form submission
   delete json_response["CO2_plot"];
   delete json_response["predictive_CO2"];
+  // Convert nulls to empty strings in the JSON response
+  if (json_response["room_capacity"] === null) json_response["room_capacity"] = '';
+  if (json_response["ventilation_lsp_values"] === null) json_response["ventilation_lsp_values"] = '';
+  // Populate the hidden input
   $("#CO2_fitting_result").val(JSON.stringify(json_response));
   $("#exhalation_rate_fit").html(
     "Exhalation rate: " +
@@ -295,10 +294,14 @@ function displayFittingData(json_response) {
   let ventilation_table = `<tr>
                             <th>Time (HH:MM)</th>
                             <th>ACH value (h⁻¹)</th>
-                            <th>Flow rate (L/s)</th>
-                            <th>Flow rate (L/s/person)</th>
-                          </tr>`;
-  json_response["ventilation_values"].forEach((CO2_val, index) => {
+                            <th>Flow rate (L/s)</th>`;
+    // Check if ventilation_lsp_values is not empty
+    let hasLspValues = json_response['ventilation_lsp_values'] !== '';
+    if (hasLspValues) {
+      ventilation_table += `<th>Flow rate (L/s/person)</th>`;
+    }
+    ventilation_table += `</tr>`;
+    json_response["ventilation_values"].forEach((CO2_val, index) => {
     let transition_times = displayTransitionTimesHourFormat(
       json_response["transition_times"][index],
       json_response["transition_times"][index + 1]
@@ -307,9 +310,12 @@ function displayFittingData(json_response) {
     ventilation_table += `<tr>
                             <td>${transition_times}</td>
                             <td>${CO2_val.toPrecision(2)}</td>
-                            <td>${json_response['ventilation_ls_values'][index].toPrecision(2)}</td>
-                            <td>${json_response['ventilation_lsp_values'][index].toPrecision(2)}</td>
-                          </tr>`;
+                            <td>${json_response['ventilation_ls_values'][index].toPrecision(2)}</td>`;
+    // Add the L/s/person value if available
+    if (hasLspValues) {
+      ventilation_table += `<td>${json_response['ventilation_lsp_values'][index].toPrecision(2)}</td>`;
+    }
+    ventilation_table += `</tr>`;
   });
 
   $("#disable_fitting_algorithm").prop("disabled", false);
@@ -419,6 +425,7 @@ function clearFittingResultComponent() {
   $referenceNode.find("#DIVCO2_fitting_result, #CO2_input_data_div").hide();
   $referenceNode.find("#DIVCO2_fitting_to_submit").hide();
   $referenceNode.find("#CO2_data_plot").attr("src", "");
+  $referenceNode.find("#warning_room_capacity_null").hide();
 
   // Update the ventilation scheme components
   $referenceNode.find("#fitting_ventilation_states, [name=fitting_ventilation_type]").prop(
diff --git a/caimira/apps/templates/base/calculator.form.html.j2 b/caimira/apps/templates/base/calculator.form.html.j2
index 9c74d295..90fbf6b0 100644
--- a/caimira/apps/templates/base/calculator.form.html.j2
+++ b/caimira/apps/templates/base/calculator.form.html.j2
@@ -370,6 +370,10 @@
                       <span class="tooltip_text">?</span>
                   </div>
                   <input type="number" id="room_capacity" class="form-control col-sm-7" name="room_capacity" placeholder="Number" min=1 form="not-submitted">
+                  <p id="warning_room_capacity_null" class="mt-2" style="display: none">
+                    <strong>Note:</strong> The maximum occupation - design limit was not defined. <br>
+                    Therefore the flow rate in liters per second per person will not be calculated.
+                  </p>
                 </div>
               </div>
 
diff --git a/caimira/apps/templates/base/calculator.report.html.j2 b/caimira/apps/templates/base/calculator.report.html.j2
index e53fdca8..5f0edad0 100644
--- a/caimira/apps/templates/base/calculator.report.html.j2
+++ b/caimira/apps/templates/base/calculator.report.html.j2
@@ -542,13 +542,16 @@
 							<li><p class="data_text">From fitting:
 							{% if form.ventilation_type == "from_fitting" %}
 							Yes</p>
-							<ul><li><p class="data_text">Room capacity: {{ form.CO2_fitting_result['room_capacity'] | int_format }}</p></li></ul></li>
+							{% if form.CO2_fitting_result['room_capacity'] %}
+								<ul><li><p class="data_text">Room capacity: {{ form.CO2_fitting_result['room_capacity'] | int_format }}</p></li></ul>
+							{% endif %}
+							</li>
 							<table class="w-50 mt-3 ml-4" border="1">
 								<tr>
 									<th> Time (HH:MM)</th>
 									<th>ACH value (h⁻¹)</th>
 									<th>Flow rate (L/s)</th>
-                            		<th>Flow rate (L/s/person)</th>
+                            		{% if form.CO2_fitting_result['room_capacity'] %}<th>Flow rate (L/s/person)</th>{% endif %}
 								</tr>
 								{% for ventilation in form.CO2_fitting_result['ventilation_values'] %}
 									{% set transition_time = form.CO2_fitting_result['transition_times'] %}
@@ -556,7 +559,7 @@
 										<td>{{ transition_time[loop.index - 1] | hour_format }} - {{ transition_time[loop.index] | hour_format }}</td>
 										<td>{{ ventilation | float_format }} </td>
 										<td>{{ form.CO2_fitting_result['ventilation_ls_values'][loop.index - 1] | float_format }} </td>
-										<td>{{ form.CO2_fitting_result['ventilation_lsp_values'][loop.index - 1] | float_format }} </td>
+										{% if form.CO2_fitting_result['room_capacity'] %}<td>{{ form.CO2_fitting_result['ventilation_lsp_values'][loop.index - 1] | float_format }} </td>{% endif %}
 									</tr>
 								{% endfor %} 
 								</table>