​One of the great approaches for cold climate countries to improve the efficiency in buildings where photovoltaic system could not be generate sufficiently, is through CHP (cogeneration of heat and power) plant.

​There is various use of the CHP plant, but most of them are used where there is a large demand in heating such as cold countries where large plants produce the heat that is distributed to buildings just by connecting to the network. Additional to natural gas, the water could be heated from biomass or even landfill waste could be incinerated to be used in another form by people. The CHP could be used for campus, hospital, or industrial complex in order to be independent from the grid. Our team, have work on an industrial project in Mexico desiring to be self-sufficient in electricity even if heating is not required, however they have a 24h manufacturing cooled facility. Thus, the CHP heat is converted into chilled water for conditioning with an absorption chiller and the electricity produced helps reduce their consumption to 45% while lowering the maximum demand load number.

​Our energy modeler experts have documented various LEED projects that take advantage of CHP plant at local or district level. The preferred approach is to model the plant directly as a heating and electricity source, this is more than simple using IESVE. The information required are the efficiency curves, the network distribution loss, and the maximum heat output from the plant. This component is connected directly to the hot water loop, or chilled water loop when using absorption chiller, to provide the required heat at each second while generating energy. We highly recommend to model the CHP instead of manually inputting the contribution to your energy results, to be able to visualize CHP plant operation and how the electricity maximum load evolves.

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​* CHP Technology, https://no.pinterest.com/pin/425027283577204903/

In a previous article - link - was presented a case study that highlighted the benefits offered by our net-zero consulting service which allowed a single-family project, designed by the environment friendly architectural firm OWN*, to save 52% in energy and provide 76% sDA, climate-based daylight calculation. In this article we will discuss a specific topic excluded from the previous one: natural ventilation for passive cooling.

Our client wanted to validate the possibility of natural ventilation cooling instead of mechanical, thus we identified that almost all days of the year around mid-day there is higher internal gain and solar gain. It was clear that there is a requirement in load and hours of operation for cooling and there could be savings in initial investment (equipment and installation) and energy saving (2%-5% annual energy consumption). 

​The method used to evaluate the design was to measure the thermal comfort (statistical person comfort considering temperature, radiation, humidity level, air velocity, clothing, and people activity). Our first evaluation considered the original design openings configuration (see left image below) which showed us that the natural ventilation cooling allows the living spaces to reach an acceptable comfort by reducing the apparent temperature 2-3 degrees Celsius. However, there was some undesirable hot spot (temperature of 30 degrees Celsius) which showed that even if on average space should be comfortable the ventilation is not sufficient. Thus, we proposed to take advantage of the modified design additional glazing, which provide better solar panel generation and increase daylight, to maximize the ventilation and natural cooling efficiency (see right image below).

​The modified design with higher glazing on the south façade allows the fresh air to enter from lower level windows and escape from higher level windows after having cooled the spaces. The reason why this is more efficient than the original design is that the supply cool air has a greater distance from the escaping hot air. As well, there was added openings on the first-floor north façade which increase the suction of cool air from the ground floor which passed from the stairway and escape from the first-floor common corridor. Increased air flows from increased higher openings and the reduced mixing of supply/escape air by strategically placing high openings resulted in a reduction of apparent temperature of 1 degree Celsius and reduction of hot spots only to few wall surfaces. Below is presented the comparison for the 2 design of temperature distribution at 1.3m from finished floor of the two floors.

Finally, please take a look at the whole simulation results:

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* OWN, Architectural Firm with focus on balance between human and nature, www.thisisown.com/.