STD and SED

Dynamic Thermal Simulation (DTS) and Dynamic Energy Simulation (DES) are hourly modeling methods (sometimes with a 10–15 minute time step) that reproduce the thermal behavior of a building over time. DTS focuses on indoor temperatures, summer comfort, and peak power demand; DES broadens the scope to include overall energy consumption (kWh, usage breakdown, monthly/annual balances). The objective is to test different building envelope options (glazing, solar shading, thermal inertia, ventilation, HVAC, BMS) and quantify their effects on comfort and energy consumption before making a final decision.

STD/SED: operational definition

A STD/SED relies on a 3D/zoned model (volumes, orientations, materials, thermal bridges), weather data (standard file or local weather), occupancy profiles (presence, internal heat gains, lighting, IT) and a detailed description of the systems (HVAC, ventilation, water treatment, controls). Different scenarios are then simulated:

- Building envelope: solar factor g, TL, insulation, inertia, tints/reflectance, EWI.

- Sun protection: sunshades, blinds, automation depending on sunlight.

- Ventilation: hygiene flow rates, night ventilation, free/night-cooling.

- Systems: Heat pumps/boilers, controls, BMS (timetables, load shedding).

The STD produces temperature curves and comfort indicators (including DH in RE2020). The SED provides energy balances (kWh per use), power demands, and allows for the evaluation of OPEX and sizing (supplementary heating, storage)

Advantages, limitations and key points of STD/SED

Interests

• Decide before investing: quantify the gain from solar protection, inertia or a new water law.
• Ensuring summer comfort: DH, peaks, need for cooling, night ventilation strategy.
• Sizing correctly: heating/cooling capacities, tank/exchanger sizes.
• Compare variants with the same weather and the same uses.

Boundaries

• Input quality = output quality: inaccurate data → misleading results.
• Study time and cost are higher than a static approach.
• Possible discrepancy with actual operation (uses, instructions, deviations).

Points to consider

• Calibration: comparing the model with measurements (counts, temperatures).
• Realistic profiles: attendance, internal contributions, schedules by area.
• Well-described systems: regulations, flow rates, ΔT, BMS scenarios.
• Reading: look at peaks as much as kWh (comfort ≠ energy alone).
• Transparency: deliver hypotheses and files for replicability.

Anecdote — “The winning shadow of Aix-en-Provence”

In Aix-en-Provence, a two-story, west-facing, glazed office building suffered from stifling afternoons. A technical design study compared three options: supplemental air conditioning, interior blinds and exterior adjustable sunshades, plus weather-controlled nighttime ventilation. The verdict: the exterior blinds and nighttime ventilation reduced the temperature difference (DH) and the required cooling capacity, resulting in lower annual kWh consumption than the "air conditioning alone" solution. The client chose the "shade + air" option; a year later, the meeting rooms showed a 1.8°C drop in peak temperature… and more peaceful meetings at 3 p.m.