How a big concrete slab can keep you warm

We are often asked about building sustainability and how do you ‘add it’ into the building. Any good architect doesn’t ‘add’ sustainability to a project, it is inherent in the design. We just do it as a matter of course. Why wouldn’t you make a building more energy efficient, cost effective and most importantly, as enjoyable to inhabit as you could? Some elements of sustainability are part of the design. They are not added items like solar panels. It includes designing for a northern orientation to allow more sunlight into the building or aligning windows to increase cross ventilation, as two examples. Thermal mass is another passive design element that improves the energy usage of your building.     The concept of thermal mass is easy - a solid wall or floor warms up in the sun- light (we have all lent against a warm brick wall on a sunny afternoon) and because of its dense mass, the wall/ floor retains that heat. In fact, it can ‘suck’ heat energy right out of the air! When the air temperature drops below the temperature of the wall or floor, it starts to release the heat energy back into the air. So, how does this help? Firstly, it stabilises the internal temperature of your room by drawing in the hot temperature and then releasing it later. In winter, we design it so the element is hit by the sunlight and warms up. It then holds that heat and re-radiates it back into the space slowly over the course of the day, warming the space.     In summer, we design the building to prevent the sunlight from hitting the wall or floor (so it doesn’t heat up from the sun) but the wall will draw in heat from the surrounding air, cooling the space. At night, as the air temperature drops, the heat is slowly released by the wall/floor and this heat can be easily flushed out of the house with cross ventilation. Energy efficiency and a more comfortable space, just by designing the building in the right manner! Or more importantly by understanding how buildings work.