Building Simulation

Vabi Elements Building simulation is the most complete simulation program that gives you optimum insight into the indoor climate of a building. The program simulates a building design for an entire year from hour to hour and provides insight into all occurring energy flows and temperatures. This is based on the chosen building properties, such as climate concepts (including climate installations and their controls), internal heat productions and structural properties. The building simulation is defined per room and per building. The Vabi Elements Building Simulation program is a dynamic building simulation program with which, among other things, hourly temperatures, weighted under and exceeded hours and the heat and cold requirements in rooms are calculated.

Vabi Elements Building simulation meets national and international standards and tests; BRL 9501, the BESTEST, the EDR according to ISSO 54 and the ASHRAE standard 140. In addition to the usual reference climate, the reference years are supplied by Vabi according to NEN 5060. The output of Vabi Elements Building simulation can be visualized in various ways, such as clear counting hours above 25 degrees Celsius, but also as weighing hours according to the prescribed criterion of the Government Buildings Agency. Of course also as PMV according to comfort theories of Fanger and ISO 7730. A comfort analysis that meets all requirements according to TO, GTO (government criterion) ATG (ISSO 74) and PMV (NEN 7730), comfort class (NEN-EN 15251) and GIW also belongs one of the many options.

Vabi Elements Building simulation gives you control over the interaction between building, organization, installation and regulations. The configurable reporting tools provide reports that you can adjust to your own preferences. Use can be made of tables, graphs, diagrams and 3D visualizations that you can define yourself. The requirement profile provides insight into the efficiency of the chosen installation concept. Different types of climate installations and their controls can be simulated in the model. It is possible to work with a central installation and with various local installations. The program is a Multi-zone and takes into account the interaction between the neighboring rooms.

Calculation based on

•     Provides insight into the interaction between building, organization, installation and regulations;

•     Dynamic calculation method tested on the basis of EDR;

•     Comfort analysis according to requirements TO, GTO (RGD criterion), ATG (ISSO74) and PMV (NEN 7730), comfort class (NEN-EN 15251) and GIW. Output including daily output graphs per component, frequency distribution of temperatures and productivity analyzes;

•     Energetic analysis based on load duration curves and requirement profiles;

•     Included reference climate files according to NEN 5060;

•     One or more installation concepts consisting of generators, distribution networks, air handling units, ventilation systems and delivery devices. Each installation concept is linked to a timetable with operating times for day, night and no operation;

•     Distribution temperatures, standard, constant or with heating lines;

•     Specifications installation concepts including setpoints, (thermal) power, supply, return and ambient temperatures;

•     Specifications air handling unit including heating and cooling batteries with limited capacity, adiabatic cooling;

•     Internal heat production (IWP) persons (including CLO and MET values, tangible, convective and latent power), equipment and lighting, linked to various time schedules;

•     Shading of, for example, the environment and facade elements;

•     Wind-dependent infiltration (qv; 10) and ventilation rates from outside the building and between the spaces themselves can be defined or automatically determined;

•     Switching levels of blinds and conditions for opening windows;

•     No restrictions on the number of departures to be calculated;

•     Intelligent irradiation calculations: the calculation of spaces behind spaces yields a realistic output.

References

Model

The model is based on Fourier comparisons. These are resolved with a fully implicit finite differential method. This method has the advantage that the solution remains stable for every node and time step. The nodes that lie on the surface of a wall have no capacity. This distribution of capacities has been chosen on the basis of the findings within TNO-Bouw and on the basis of the thesis of P.J.J. Hoen "Energy consumption and indoor environment in residences", pages 5.13 and 5.14 (Figure 1). The matrix solution method chosen does not depend on the capacity distribution, so that it can possibly be changed. To calculate all temperatures in a room, a room matrix and several wall matrices are set up in the model. A wall matrix contains the capacities in a wall and the guidance within that wall. The departure matrix contains the radiation and convective exchange between the surface layers of the walls and the air node within the room. Many other models work with a large matrix that contains the entire system of walls and an air node in the room. However, this results in a large matrix that is empty in many places. Working with a departure matrix and several wall matrices has the advantage that the required memory space remains limited.

Results

Temperature overruns are counted only during the operating time (counting hours). In assessing the overruns, criteria (space requirements) are used, which are based on thermal comfort. The building simulation assumes the theory of Fanger. The comfort parameters in Fanger's model are divided into two groups:

• Parameters that concern the person, such as the heat resistance of the clothing and the heat development in the person (metabolism);

• Parameters that concern the environment, such as air temperature, radiation temperature, humidity and air velocity.

A used criterion is to allow overrun of the predicted mean vote (PMV) = 0.5 and underwriting of PMV =-0.5. In this criterion, the number of hours that a given PMV is exceeded is multiplied by a weighing factor and summed. As a guideline for the maximum number of weighing hours per year, 150 hours for exceeding PMV = 0.5 (for summer) and 150 hours for underwriting of PMV =-0.5 (for winter) can be maintained.

The aforementioned number of hours exceeding 25 °C or the number of weighing hours do not apply as absolute value but as guideline values. It is not that a building with 149 weighing hours is good and a building with 151 weighing hours is bad. When calculating the PMV value, both the calculated air and the calculated radiation temperature are used. The calculation of the PMV value for the determination of exceedations usually assumes a relative humidity of 50%, an air velocity of 0.15 m/s, a heat resistance of the clothing of 0.9 CLO in winter and 0.7 CLO in the summer and a Metabolism of 1.2 WITH.