The Law of Conservation of Energy
The first of the 3 Laws of Thermodynamics, known also as the Law of Conservation of Energy, states that energy can neither be created nor destroyed. It only changes form (apart from at the Quantum level, but let’s not get into that!).
The way in which energy in a building changes form and moves is of great interest to those designers who use this information to best plan construction projects. The thing is, these are really complex system. With the capacity of computers to perform a multitude of calculations (a task in this context practically impossible by humans), digital simulation software can help designers to understand vastly complex relationships of cause and effect between building materials, humans and the environment.
Environmental Design in our built environment
Environmental design has existed in buildings since the first cave dwellers used geothermal heat from the earth to keep warm, to the use of natural ventilation and the storage of the Suns energy with thermal mass walls in vernacular architecture.
An example of environmental design is the positioning of buildings, and particularly their windows, to orrient towards the Sun, occupants can benefit from free energy in the form of solar gain.
In order to understand the behaviour of buildings, environmentally speaking, designers perform digital simulations to study heat gain, air flow directions, thermal performance of the building materials and the effects of occupants and energy producing equipment on the internal environment.
Testing multiple design options
One way that building energy simulations may be used in an optimised design environment is to compare various design alternatives. For the purposes of the Proleek project, three design options will be compared for the restoration of the cottage, based on suitable designs for the building type, traditional solid stone wall. These are categorised as:
1) Minimal intervention
2) Medium intervention, and
3) Considerable intervention
Following the preparation of the design models in Autodesk Revit 2016, using the ‘design options’ function (allowing for multiple variations on arrangement) the Architectural Building Information Model will be transferred to simulation software through the open source gbXML file format which translates spaces and surfaces into a simulateable form.
The spatial and thermal properties of the designs will be used directly in both EDSL TAS Simulator and Solar Computer. This step will be dealt with in detail in a later post, but suffice to say that for the research project, the aim is to automate as much as possible in this workflow, allowing for many itterations leading to optimised design.
The image below shows the various ways that heat and energy are transferred in buildings. The calculation of the effect of all of these processes combined is known as a thermodynamic simulation.
For the thesis project I will be using EDSL TAS Simulator to learn the heating and cooling loads throughout the year. Solar Computer will then be used to calculate the worst case scenarios on the hottest and coldest days of the year, for the purpose of sizing the capacity of the energy producing systems (mechanical or other… ie. fireplace?) required to sustain thermal comfort in the building.
Initial results for design option 1
The results are in!!! An initial test run has been completed for the first option of the Proleek cottage which sees the building resorted to its original form with no additional insulation. The simulation in EDSL TAS Simulator calculates the thermodynamic movement for every hour over an entire year based on statistical weather data for the region. The colours represent the energy within the space. We can see the Sun arc moving accross the sky as the year progresses and falling again towards winter. This shows us the heat naturally captured by the building from the environment.
On a final note, there are 8760 hours in a year…
I have learned this due to the following critisism. No doubt that the EDSL TAS Simulation software is very powerful and the output is in the form of rather attractive 3D environment on top of the usual graphs, charts and spreadsheets. Having said this, the program does not have a function to record or ‘play’ through the simulation. In order to create the above video I had to click very quickly 8760 times (taking a solid 26 minutes!) through each hour of the day while recording the screen (this was later sped up x8, ’cause who’s got 26 minutes?) It would be a welcome adition to the software!