NREL Interview Questions and Answers

Career Goals.  Why work at NREL?

Why do you want to work at NREL?  Why do you want to work in Commercial Buildings in particular?  How does this job fit into your longer term career goals? Please take a look at this website for more information about the work done here at NREL in the commercial buildings area.

I believe that in the coming decades providing the plentiful energy which is currently synonymous with a high standard of living is likely to be a serious problem for humanity, and more generally for the terrestrial biosphere.  Today our energy is derived overwhelmingly from fossil fuels which are polluting, finite, unevenly distributed, and whose combustion is substantially altering the composition and optical properties of the Earth’s atmosphere.  Any one of those characteristics would be enough to cause grave concern.  Together they make significant change in our global energy systems imperative.  I want to be a part of that change.

In thinking about how I might most effectively contribute to this necessary transformation I’ve considered the potential for increasing renewable energy supplies, and for reducing demand from either our transportation systems or the built environment, keeping in mind the skills which I have acquired, and the kind of work that I enjoy.  I’ve settled on increasing the efficiency of the built environment for a variety of reasons.  First, while developing renewable energy sources is a vital part of ensuring a stable energy future, within the current regulatory regime they are not cost-competitive with fossil fuels, and even if we succeed in overhauling the regulatory regime in the developed world, fossil fuels may well remain the cheapest option in those parts of the world where energy demand is most rapidly growing.  To have a large impact renewables will thus either need to end up cheaper than coal in China, or else the amount of energy required to sustain what we consider a high standard of living will have to decrease to the point where the extra expense of using renewable energy is not a significant deterrent.  Increases in end use efficiency will in any case be beneficial, many available efficiency measures already make economic sense, and I believe the untapped potential for increased energy efficiency throughout our economy is generally underestimated.  From a personal point of view, I’d also rather work on something I know will prove fruitful, without having to hope for a breakthrough.

I’ve chosen to focus on the built environment instead of transportation because I believe that the right way to make transportation less energy intensive is not to change how we build and power our cars, but to make transportation largely unnecessary by building our cities at a scale and density that makes human powered transportation pleasant and convenient, and investments in public transit economically sensible.  I believe that effecting these changes in our urban environments is largely a political, regulatory, and social challenge, not a technical one.  I intend to continue advocating for better cities as a citizen, but I don’t want to make that my primary vocation.

These three domains are also subject to very different market and regulatory pressures.  Motor vehicles are mass produced, made by only a few manufacturers, and are generally regulated at the state or national level.  All of those properties make changing the vehicle market difficult, because manufacturing cars today involves large capital expenditures to tool a plant, and a few large interests (the automakers and the petroleum industry) which can very effectively organize to lobby policymakers at the state or national level.  Similarly the utilities and power generators tend to be regulated at the state and national level, not particularly competitive or dynamic, subject to large capital investments with long depreciation times, and able as industries to effectively lobby the policymakers with power over them.  In contrast, building codes and zoning regulations are often set by cities and counties, and there are many thousands of architecture firms, construction companies and building contractors, making localized regulatory experimentation possible, and competition within the building industry vigorous.  Buildings, especially commercial buildings, are also not generally mass produced, and so prior to construction there are no large sunk capital costs which need to be depreciated, meaning each project is potentially a blank slate for innovation, constrained only by the creativity of the designers, available construction techniques and materials, and our understanding of how building systems function.  This is the kind of open and dynamic marketplace I want to be a part of.

Beyond any of the rational considerations above, I am also drawn to passive architecture aesthetically.  A load bearing arch still standing in a two thousand year old Roman aqueduct has a deeper beauty than a construction of a similar shape that carries no weight but its own, or an entirely decorative arch not even under compression.  Biological systems and structures which have evolved under harsh selective pressure have this kind of functional beauty, and often purely aesthetic beauty as well.  I think buildings should be more like organisms, evolved to regulate their own temperatures and airflows, to illuminate their own interiors, and even to collect their own water and treat their own wastes.  Ultimately they should do these things as natural consequences of their design, without net inputs of energy other than the sunlight that falls on them.  Such buildings have enduring beauty and utility that purely artistic designs free from functional constraint can never achieve.

I have two long term career goals that are well served by working with EnergyPlus at NREL.  First a technical goal: I believe that we are grossly under utilizing the processing power which is now widely available, by applying it mostly using linear brute force methods, without creating frameworks within which the machines can efficiently and selectively explore parameter spaces, adapting their searches based on what they find.  Synthetic biologists are starting to collaborate with evolution, alternating between artificial selective pressures and explicit deconstruction and redesign of metabolic pathways, for e.g. the production of cellulosic biofuels.  Many design problems should be susceptible to the same general technique, and I would eventually like to see that kind of approach used in architecture.  Given a building site, and functional, regulatory, and cost constraints, it should be possible to evolve a building from some initial design sketch to an optimal design based on the outcomes of many simulations, learning lessons about what works and what doesn’t, and making design alterations and suggestions throughout the process.

Second, a big picture goal: China is urbanizing at a rate unprecedented in human history.  In the next few decades hundreds of millions of people are going to move from the countryside to cities that don’t even exist today.  Those cities are going to be built from scratch, and it is very important that they get built the right way the first time around.  I hope to help China urbanize sustainably, either via intergovernmental cooperation from within the DoE, by working through an NGO like the Rocky Mountain Institute, or as part of a private enterprise.  I enjoy studying foreign languages, and I intend to learn Mandarin in order to be able to effectively collaborate on projects with Chinese engineers, designers, and officials.

Working at NREL is especially attractive because as a governmental agency not primarily concerned with profits, there should be more opportunity for openly sharing the techniques and tools I hope to be working on, and thus having a broader impact on building systems than would be possible working for a commercial entity with a large incentive to keep their innovations under proprietary control, and thus in limited use.  I am a strong advocate of open systems and standards for interoperability, and believe that helping to set those market standards is one of the most valuable things that government can do.  I’m also attracted to NREL because I fell in love with the culture and climate of the city of Boulder when I came to the University of Colorado for graduate school, and I look forward to being able to live there and commute to work by bus and bike.


Tell me about your technical education or any coursework related to Buildings and Thermal Systems.

My undergraduate degree from Caltech is in Engineering and Applied Science, with a concentration in computer science.  Caltech’s core course requirements included a broad sampling of physical sciences including classical mechanics, electromagnetism, thermodynamics, statistical and quantum mechanics, and three years of math, including calculus, linear algebra, probability and statistics, complex analysis, and techniques for solving both ordinary and partial differential equations.  I fulfilled the engineering requirements with a variety of courses, but especially enjoyed those focused on adaptive systems such as neural networks and artificial life, whose specifications are simple, but which have complex emergent behavior.

My graduate degree at the University of Colorado in Boulder will technically come from the department of Geological Sciences department, but most of my research and coursework has been more related to planetary scale physical processes which are not traditionally considered by geologists.  I especially enjoyed cosmochemistry, which among other things, explored the thermal evolution of bodies within the early solar system, as a result of heat released from the decay of short-lived radioisotopes.  I also took a course in planetary atmospheres, which discussed the different kinds atmospheric circulations resulting from conservation of angular momentum, convective instabilities, adiabatic cooling, condensation of volatiles, etc. and a course in planetary interiors, dealing with phase changes and equations of state in both solid and fluid bodies, fluid and solid state convection, gravitational differentiation, and other basic physical processes that determine the structure and behavior of planetary bodies.

Building Research and Technical Experience

Tell me about your building research experience.  Tell me about how you would apply your technical experience to Buildings and Thermal Systems.

I do not have direct technical experience with building science or architecture.  However, the physical processes which govern the behavior of planets and of buildings are not ultimately different.  Diffusion, convection, and radiation can’t tell what kind of system they’re part of.  Networks of springs and dashpots, complex rheologies, and RLC circuts are all described by the same math.  My programming, computer science, and physical modeling experience would have direct applicability.


Tell me about your experience working with teams in a technical work environment.

Unfortunately I have had very little experience working as a part of a technical team.  My group at SCO was fragmented and had a high turnover rate, and my interactions with them seemed primarily to consist of attempting to absorb information from other members as quickly as possible, before they left for another job.  This didn’t leave me with much depth of knowledge about the legacy systems I was supposed to be maintaining, or much connection to the group, or ultimately, the job.

My work at Caltech involved little in the way of technical collaboration.  My programming and systems administration tasks were fairly self-contained, and I was expected to manage them on my own, and deliver the products of my labors in a functional state.

My research experiences have, similarly, been isolated.  None of the research groups I have been a part of have had more than 3 students in them, and none of my projects has ever been more than very peripherally related to those of the other students.  In the collaborations I’ve had with faculty our interactions have been mostly either scientific or editorial, and not technical per se.  I’ve enjoyed having someone to talk to about ideas and the ways to approach a problem or conceptualize a system, but the technical architecture and implementation has always been entirely under my control.

Honestly, I’m really looking forward to being part of a team.  I’m happier and more productive when I can share my joys and frustrations with other people who understand what I’m working on, and my graduate career has been altogether too isolated.

Technical Problem Solving Skills

Give me an example of a specific technical problem you solved.  Tell me (briefly) what the problem was, what YOU did about it and how the situation was resolved including evidence about how you knew the problem was solved.

For one of my research projects I had to perform a directed search of a large parameter space, and I chose to implement a technique called the neighborhood algorithm, which divides the parameter space up into nearest neighbor cells surrounding the existing samples.  Once I had the code working, I gave it some relatively simple problems the answers to which I already knew, in order to verify that it the implementation was correct.  I gradually increased the number of parameters it had to optimize for, and when all seemed well, I ran it on the main problem: simulating fractures in the ice of Jupiter’s moon Europa due to tidal stresses, which matched the shapes of observed fractures, and it successfully produced synthetic features very similar to the mapped features.

I recently had to determine whether the unevenly distributed observations we have of the surface of Jupiter’s moon Europa had introduced any bias into the map which I’d made of tectonic features, and thus whether the results of another analysis were really generalizable to the body as a whole.  I decided to measure the correlation between my observations of tectonic features (lineaments), and the four observational variables available (image resolution, and the incident, emission, and phase angles of the observation).  Initially I simply divided up the the surface into a bunch of two dimensional histrogram bins, and counted the number of tectonic feature observations in each bin, and the correlated those counts with the values of the observational variables, but this resulted in suspiciously extreme values near the poles, which I then realized was because the map I’d been dividing into lat/lon bins was projected, and that the bins near the poles actually had much smaller areas than those near the equator.  I got around this by calculating the sum of the lengths of the tectonic features within a given (spherical) distance of several thousand randomly chosen, evenly distributed points on the surface of the moon.  Because in this case all the observations were single points, instead of areas, and I was able to force the distribution of points to be evenly distributed over the sphere, no geometric biases were possible.  It turned out there was no significant bias introduced into my map from the uneven distribution of observations.

Technical Writing

Tell me about your technical writing experience. What kinds of technical documents have you written or been involved with.

I’ve written parts of NASA research proposals, source code and software documentation, and scientific journal articles.  I’ve also written and presented numerous talks about my research ranging from 10 minutes to one hour in length.  I’ve done poster presentations at the American Geophysical Union fall meeting in San Francisco, the Lunar and Planetary Science Conference in Houston.  I’ve also given talks and slideshows on planetary exploration to grade school kids, taught the occasional astronomy or planetary science course when the professor I was TAing for was out of town, and held numerous homework help and test review sessions.

Project Management experience:

Tell me about your project management experience.

The only projects I’ve ever managed have been my own research and software development, which have largely been without externally imposed time or resource constraints, and are thus probably not good measures of my ability to manage projects within a structured environment having external dependencies.

Salary requirements

What is your current or last salary (keeping in mind that this is not a salary negotiation but rather NREL’s way of making sure you should be considered for this job).  What are your salary requirements?  Are these salary requirements negotiable.

My last relevant annual salary was $52,000 in the year 2000, when I was working as a software build and integration engineer for the Santa Cruz Operation (SCO).  Assuming annual cost of living adjustments of 3%, I estimate that an equivalent salary today would be roughly $65,000.  This amount is negotiable, especially if you provide significant matching monies for a portable retirement account (401(k), 403(b), TIAA-CREF annuity, etc.) or the possibility of substantial unpaid leave.


If you have not done so already, please provide your transcripts along with your answers. Unofficial copies are okay for now

Attached please find a copy of my unofficial transcript from the University of Colorado at Boulder.  I was not able to obtain a copy of my Caltech transcript on short notice, but of course I will arrange to have official copies sent to you in the event that you decide to offer me a job.

Work Eligibility

Are you eligible to work in the US? Do you requirement sponsorship to work at NREL? Are you a citizen of the US? (This last question is asked for site access purposes only).

I am a US citizen, and thus eligible for employment at NREL.

Confirmation of Interest

Are you interested in being considered for this position? When would you be able to begin working for us if offered a position?

I am still very interested.  I will be available for work beginning on July 6th, 2009.

Edge Question

What skills or experiences do you feel you offer to this position above and beyond the job requirements?

My extensive travel, study of several foreign languages, and of planetary systems in the general sense has given me an unusually global perspective on the resource problems facing humanity, and everyone else we share this place with.  I think I also have a better understanding of finance and economics than the average scientist or engineer, and I have a real interest in the non-technical aspects of energy efficiency issues.  Too often those interested in purely technical problems can be oblivious to what non-technical constraints the system in question may be subject to – whether it’s cost effective, whether it can scale well, political realities, etc.  I hope that will not be the case with me.

By Zane Selvans

A former space explorer, now marooned on a beautiful, dying world.

10 replies on “NREL Interview Questions and Answers”

hi there, I came across your post while I was researching NREL job-related matters. thanks for the excellent post. if you can spare the time, i’m hoping you can help me with a few questions I have. I have recently applied for a few positions at NREL and am very curious about their hiring procedure, such as…

– how long before you hear back from them after your application submission? i’m keeping track of my application via their online service. one job already says ‘does not meet qualifications’ (rightfully so. i don’t have the work experience required but the work description was very much close to my training so i decided to apply for it). All the rest say resume has been received

– how do you think they feel about multiple applications? i applied for a number of positions, but only because I felt they were all positions I would be happy to work in. I have 2 top choices that i was absolutely ecstatic about, but was is better to apply for the 2 only?

– 1 of the positions I applied for was re-listed again today. Do you think that means something?

– should i be engaged in any follow-up activity?

thanks much for reading through my questions, i would be happy if you can answer any of them for me. I am not sure if you talked about the interview elsewhere, but I’m curious about the format. Were they written questions? through email or so?

thanks again, and I hope you were successful in your application

Ha! I wish I knew. I actually had an on-site interview in January (I was in Colorado anyway) and they said they’d get back to me within a month or so, and they never did. I made a point of contacting the hiring manager a couple of times afterward so they would know I was still interested, and they still never got back to me with a definitive ‘yes’ or ‘no’. I’m assuming at this point (5 months later) that it’s a ‘no’!

With just about any job application process, I think that to have a real chance, you have to know someone, or at least make personal contact with somebody via e-mail, phone, in person at a conference, etc. Resumes and applications that appear out of the ether are pretty heavily discounted, as they perhaps should be.

I wouldn’t worry too much about the re-listed jobs. NREL has thankfully been hiring at breakneck pace lately, and they have many open positions with nearly identical descriptions.

Hey there!
Have you not heard from NREL still? I applied for a position and had an on-site interview with NREL about a month and a half ago. I have been in touch with the senior staffing consultant (HR head honcho) several times over the phone and email. I was the first of 5 or 6 to be interviewed for 3 positions so I new they would take a while to get back, but now I’m wondering after reading your post… Have you heard of other similar relations with NREL and potential employees?


I haven’t heard back, and at this point, obviously, I don’t ever expect to. I’ve been told that even if they do end up hiring you, the lag can be quite a while, so I wouldn’t despair yet. Just stay in touch with the hiring people and make sure they keep you updated on the situation.

NREL usually hires people who come with their own funding. Otherwise you can toil as a Contractor for a few years and win the affection of a few key people who do have money.

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