Category: Engineering

Isobaric processes

Isobaric processes

Isobaric process

12/17/17

“What is a thermodynamic process in which pressure remains constant?”

 

One of the defining features of a thermodynamic process is that the state of the system will change with time. However, in some of these processes, not all of the properties of a state will change. An example is Isobaric Processes, in which the pressure of a system will stay constant throughout the process. The work done under an isobaric process can be very simple to compute, being proportional to the change of volume W = P(v2-v1).

California Title 24

California Title 24

California Title 24

12/17/17

“What is the official building energy efficiency standard for California?”

 

In the U.S, most building efficiency standards are regulated by ASHRAE 90. However, some states go a little bit further with their regulations. In California, a series of codes known as Title 24 is the law of the land. Title 24 contains all of the specifications that a construction firm must consider before going through with a project. These include a requirement for LED lights, motion sensors for buildings, a specified minimum reflectivity for roofs,  electrical service panels for disaggregated measurement, and many other variables. California Title 24 is updated every 3 years such that the next set of rules saves more energy than the last.

Energy Recovery Ventilation

Energy Recovery Ventilation

Energy Recovery Ventilation

12/15/17

“How can we use stagnant building air to do something productive?”

 

When air is trapped inside a building for too long, it can become unhealthy and stagnant. However, could we possibly use our engineering mindsets to do something productive with this? Well, we know that heat exchangers can be used to make use of any fluids. And oftentimes, incoming air into buildings is suboptimal. So what if we were to use a heat exchanger to cycle the external air with the old interior air to keep our building fresh? This system is known as  Energy Recovery Ventilation and holds much promise for the future of the HVAC industry.

Electric Sub-Panels

Electric Sub-Panels

Electric Sub-Panels

12/15/17

“How can we distribute electricity in a larger building?”

 

Electrical service panels are ubiquitous in integrating an edifice to the grid. However, sometimes a building unit can become too large for just one subpanel. However, what if instead we were to just hook up a smaller panel to the larger one? Think of it like attaching a multi-plug to an outlet. These Electric Sub-Panels can now be found in built environments all over the world.

Electrical Service Panels

Electrical Service Panels

Electrical Service Panels

12/14/17

“What connects a house to the grid?”

 

Electricity from the grid has made modern living much better, whether it be in the lights that allow us to stay up late into the night, the HVAC systems that keep our place cool, or the energy that powers our computers. However, what exactly connects these services to our built environment? Well, let’s use our engineering mindset to think of it.

 

First, we will need a central location to keep all of the connecting circuits. This will allow us to centrally deliver power throughout a unit. We must also keep in mind that a circuit overload may occur, in which case circuit breakers will be attached. Now let’s place all of these in a central frame, making a device called an Electrical Service Panel. Electric Service Panels are one of the foundations of modern home energy systems and can be found in nearly every grid-connected building.

Building Integrated Photovoltaics

Building Integrated Photovoltaics

Building Integrated Photovoltaics

12/13/17

“How can we directly integrate photovoltaics into a building?”

 

Solar photovoltaic panels have revolutionized energy as we know it. And since buildings are some the highest consumers of energy, it would only be logical that panels be applied to them. But PV systems can be big and clunky and take up a lot of room.

 

Or do they have to?

 

Novel breakthroughs have resulted in the creation of a technology known as Building Integrated Photovoltaics (BIPs). These systems are directly integrated into the building envelope, allowing for much more flexible use. They can be put directly on rooftops, applied to the sides, or even constructed as transparent windows! However, there are numerous factors to consider when using building integrated photovoltaics. Shading may occur from other edifices, there may be deposition from weather, and a proper tilt angle depending on the geographic location must all be considered. Despite this, BIPs are an excellent foray for humanity into greater sustainability.

Disaggregated Measurement

Disaggregated Measurement

Disaggregated Measurement

12/11/17

“How does California specify how all building loads must be measured?”

 

Most areas of the developed world have stringent building energy standards that include analysis for measurement. And as such, California is no exception. But it does so in a very special way. California title 24 (the building energy codec) stipulates that all new buildings must sort their energy loads (HVAC, lighting, etc.) into discrete piles in a method known as Disaggregated Measurement. This way, each subset can be monitored for its energy consumption.

ASHRAE Standard 90.1

ASHRAE Standard 90.1

ASHRAE Standard 90.1

12/10/17

“What is the basis for building energy efficiency in the U.S and much of the world?”

 

With the onset of global warming, energy efficiency has become a great necessity. As such, buildings in the U.S must now follow a certain standard so that after construction they will meet the sustainability requirements dictated by ASHRAE Standard 90.1. ASHRAE Standard 90.1 is a compilation of all of the codes for building energy efficiency (with the exception of low rise residential units) and is updated every three years to ensure that the next set of codes will be 15 percent more efficient than the previous.

Stirling Cycle

Stirling Cycle

Stirling Cycle

12/09/17

“How can we describe the operation of a Stirling Engine?”

 

Stirling Engines are very interesting machines. However, how exactly can we describe how they operate? Well, let’s use our engineering mindset to find out. First, let’s start with an isothermal expansion in which the working fluid is heated by an external source in Phase 1. Then, let’s go through a constant volume heat removal by passing the working fluid through a regenerator in Phase 2. Afterwards, the system should undergo an isothermal compression in Phase 3. This will lead up to Phase 4, a constant volume heat addition bringing the working fluid back to the beginning of the Stirling Cycle. Stirling cycles operate much like Carnot cycles except that their heat addition/removal process is constant volume.